import macros;macro ImportExpand(s:untyped):untyped = parseStmt($s[2])
# source: https://github.com/kemuniku/cplib/tree/main/src/cplib/tmpl/citrus.nim
ImportExpand "cplib/tmpl/citrus" <=== "when not declared CPLIB_TMPL_CITRUS:\n    const CPLIB_TMPL_CITRUS* = 1\n    {.warning[UnusedImport]: off.}\n    {.hint[XDeclaredButNotUsed]: off.}\n    import os\n    import algorithm\n    import sequtils\n    import tables\n    import macros\n    import std/math\n    import sets\n    import strutils\n    import strformat\n    import sugar\n    import streams\n    import deques\n    import bitops\n    import heapqueue\n    import options\n    import hashes\n    const MODINT998244353* = 998244353\n    const MODINT1000000007* = 1000000007\n    when not declared CPLIB_UTILS_CONSTANTS:\n        const CPLIB_UTILS_CONSTANTS* = 1\n        const INF32*: int32 = 100100111.int32\n        const INF64*: int = int(3300300300300300491)\n    \n    const INFL = INF64\n    type double* = float64\n    let readNext = iterator(getsChar: bool = false): string {.closure.} =\n        while true:\n            var si: string\n            try: si = stdin.readLine\n            except EOFError: yield \"\"\n            for s in si.split:\n                if getsChar:\n                    for i in 0..<s.len():\n                        yield s[i..i]\n                else:\n                    if s.isEmptyOrWhitespace: continue\n                    yield s\n    proc input*(t: typedesc[string]): string = readNext()\n    proc input*(t: typedesc[char]): char = readNext(true)[0]\n    proc input*(t: typedesc[int]): int = readNext().parseInt\n    proc input*(t: typedesc[float]): float = readNext().parseFloat\n    macro input*(t: typedesc, n: varargs[int]): untyped =\n        var repStr = \"\"\n        for arg in n:\n            repStr &= &\"({arg.repr}).newSeqWith \"\n        parseExpr(&\"{repStr}input({t})\")\n    macro input*(ts: varargs[auto]): untyped =\n        var tupStr = \"\"\n        for t in ts:\n            tupStr &= &\"input({t.repr}),\"\n        parseExpr(&\"({tupStr})\")\n    macro input*(n: int, ts: varargs[auto]): untyped =\n        for typ in ts:\n            if typ.typeKind != ntyAnything:\n                error(\"Expected typedesc, got \" & typ.repr, typ)\n        parseExpr(&\"({n.repr}).newSeqWith input({ts.repr})\")\n    proc `fmtprint`*(x: int or string or char or bool): string = return $x\n    proc `fmtprint`*(x: float or float32 or float64): string = return &\"{x:.16f}\"\n    proc `fmtprint`*[T](x: seq[T] or Deque[T] or HashSet[T] or set[T]): string = return x.toSeq.join(\" \")\n    proc `fmtprint`*[T, N](x: array[T, N]): string = return x.toSeq.join(\" \")\n    proc `fmtprint`*[T](x: HeapQueue[T]): string =\n        var q = x\n        while q.len != 0:\n            result &= &\"{q.pop()}\"\n            if q.len != 0: result &= \" \"\n    proc `fmtprint`*[T](x: CountTable[T]): string =\n        result = x.pairs.toSeq.mapIt(&\"{it[0]}: {it[1]}\").join(\" \")\n    proc `fmtprint`*[K, V](x: Table[K, V]): string =\n        result = x.pairs.toSeq.mapIt(&\"{it[0]}: {it[1]}\").join(\" \")\n    proc print*(prop: tuple[f: File, sepc: string, endc: string, flush: bool], args: varargs[string, `fmtprint`]) =\n        for i in 0..<len(args):\n            prop.f.write(&\"{args[i]}\")\n            if i != len(args) - 1: prop.f.write(prop.sepc) else: prop.f.write(prop.endc)\n        if prop.flush: prop.f.flushFile()\n    proc print*(args: varargs[string, `fmtprint`]) = print((f: stdout, sepc: \" \", endc: \"\\n\", flush: false), args)\n    const LOCAL_DEBUG{.booldefine.} = false\n    macro getSymbolName(x: typed): string = x.toStrLit\n    macro debug*(args: varargs[untyped]): untyped =\n        when LOCAL_DEBUG:\n            result = newNimNode(nnkStmtList, args)\n            template prop(e: string = \"\"): untyped = (f: stderr, sepc: \"\", endc: e, flush: true)\n            for i, arg in args:\n                if arg.kind == nnkStrLit:\n                    result.add(quote do: print(prop(), \"\\\"\", `arg`, \"\\\"\"))\n                else:\n                    result.add(quote do: print(prop(\": \"), getSymbolName(`arg`)))\n                    result.add(quote do: print(prop(), `arg`))\n                if i != args.len - 1: result.add(quote do: print(prop(), \", \"))\n                else: result.add(quote do: print(prop(), \"\\n\"))\n        else:\n            return (quote do: discard)\n    proc `%`*(x: SomeInteger, y: SomeInteger): int =\n        result = x mod y\n        if y > 0 and result < 0: result += y\n        if y < 0 and result > 0: result += y\n    proc `//`*(x: SomeInteger, y: SomeInteger): int =\n        result = x div y\n        if y > 0 and result * y > x: result -= 1\n        if y < 0 and result * y < x: result -= 1\n    proc `^`*(x: SomeInteger, y: SomeInteger): int = x xor y\n    proc `&`*(x: SomeInteger, y: SomeInteger): int = x and y\n    proc `|`*(x: SomeInteger, y: SomeInteger): int = x or y\n    proc `>>`*(x: SomeInteger, y: SomeInteger): int = x shr y\n    proc `<<`*(x: SomeInteger, y: SomeInteger): int = x shl y\n    proc `%=`*(x: var SomeInteger, y: SomeInteger): void = x = x % y\n    proc `//=`*(x: var SomeInteger, y: SomeInteger): void = x = x // y\n    proc `^=`*(x: var SomeInteger, y: SomeInteger): void = x = x ^ y\n    proc `&=`*(x: var SomeInteger, y: SomeInteger): void = x = x & y\n    proc `|=`*(x: var SomeInteger, y: SomeInteger): void = x = x | y\n    proc `>>=`*(x: var SomeInteger, y: SomeInteger): void = x = x >> y\n    proc `<<=`*(x: var SomeInteger, y: SomeInteger): void = x = x << y\n    proc `[]`*(x, n: int): bool = (x and (1 shl n)) != 0\n    proc `[]=`*(x: var int, n: int, i: bool) =\n        if i: x = x or (1 << n)\n        else: (if x[n]: x = x xor (1 << n))\n    proc pow*(a, n: int, m = INF64): int =\n        var\n            rev = 1\n            a = a\n            n = n\n        while n > 0:\n            if n % 2 != 0: rev = (rev * a) mod m\n            if n > 1: a = (a * a) mod m\n            n >>= 1\n        return rev\n    when not declared CPLIB_MATH_ISQRT:\n        const CPLIB_MATH_ISQRT* = 1\n        proc isqrt*(n: int): int =\n            var x = n\n            var y = (x + 1) shr 1\n            while y < x:\n                x = y\n                y = (x + n div x) shr 1\n            return x\n    \n    proc chmax*[T](x: var T, y: T): bool {.discardable.} = (if x < y: (x = y; return true; ) return false)\n    proc chmin*[T](x: var T, y: T): bool {.discardable.} = (if x > y: (x = y; return true; ) return false)\n    proc `max=`*[T](x: var T, y: T) = x = max(x, y)\n    proc `min=`*[T](x: var T, y: T) = x = min(x, y)\n    proc at*(x: char, a = '0'): int = int(x) - int(a)\n    proc Yes*(b: bool = true): void = print(if b: \"Yes\" else: \"No\")\n    proc No*(b: bool = true): void = Yes(not b)\n    proc YES_upper*(b: bool = true): void = print(if b: \"YES\" else: \"NO\")\n    proc NO_upper*(b: bool = true): void = Yes_upper(not b)\n    const DXY* = [(0, -1), (0, 1), (-1, 0), (1, 0)]\n    const DDXY* = [(1, -1), (1, 0), (1, 1), (0, -1), (0, 1), (-1, -1), (-1, 0), (-1, 1)]\n    macro exit*(statement: untyped): untyped = (quote do: (`statement`; quit()))\n    proc initHashSet[T](): Hashset[T] = initHashSet[T](0)\n"
# source: https://github.com/kemuniku/cplib/tree/main/src/cplib/modint/modint.nim
ImportExpand "cplib/modint/modint" <=== "when not declared CPLIB_MODINT_MODINT:\n    const CPLIB_MODINT_MODINT* = 1\n    when not declared CPLIB_MODINT_MODINT_BARRETT:\n        const CPLIB_MODINT_MODINT_BARRETT* = 1\n        import std/macros\n        type StaticBarrettModint*[M: static[uint32]] = object\n            a: uint32\n        type DynamicBarrettModint*[M: static[uint32]] = object\n            a: uint32\n        type BarrettModint* = StaticBarrettModint or DynamicBarrettModint\n    \n        proc get_im*(M: uint32): uint = cast[uint](-1) div M + 1\n        func get_param*[M: static[uint32]](self: typedesc[DynamicBarrettModint[M]]): ptr[tuple[M, im: uint]] =\n            {.cast(noSideEffect).}:\n                var p {.global.}: tuple[M, im: uint] = (998244353u, get_im(998244353u32))\n                return p.addr\n        template get_M*(T: typedesc[BarrettModint]): uint =\n            when T is StaticBarrettModint: T.M.uint\n            else: (get_param(T))[].M.uint\n        proc setMod*[T: static[uint32]](self: typedesc[DynamicBarrettModint[T]], M: SomeInteger or SomeUnsignedInt) =\n            (get_param(self))[] = (M: M.uint, im: get_im(M.uint32))\n    \n        template umod*[T: BarrettModint](self: typedesc[T] or T): uint32 =\n            when self is typedesc:\n                when self is StaticBarrettModint: self.M\n                else: cast[uint32](((get_param(self))[]).M)\n            else: T.umod\n        template `mod`*[T: BarrettModint](self: typedesc[T] or T): int32 = (T.umod).int32\n        {.emit: \"\"\"\n        #include <cstdio>\n        inline unsigned long long calc_mul(const unsigned long long &a, const unsigned long long &b) {\n            return (unsigned long long)(((__uint128_t)(a) * b) >> 64);\n        }\n        \"\"\".}\n        proc calc_mul*(a, b: culonglong): culonglong {.importcpp: \"calc_mul(#, #)\", nodecl, inline.}\n        proc rem*(T: typedesc[BarrettModint], a: uint): uint32 =\n            when T is StaticBarrettModint:\n                const im = get_im(T.M)\n                const M = get_M(T)\n                var x = (calc_mul(cast[culonglong](a), cast[culonglong](im))).uint\n                var r = a - x * M\n                if M <= r: r += M\n                return cast[uint32](r)\n            else:\n                var p = get_param(T)[]\n                var x = (calc_mul(cast[culonglong](a), cast[culonglong](p.im))).uint\n                var r = a - x * p.M\n                if p.M <= r: r += p.M\n                return cast[uint32](r)\n        proc init*(T: typedesc[BarrettModint], a: T or SomeInteger): auto =\n            when a is T: return a\n            else:\n                if a in 0..<T.mod.int: return T(a: a.uint32)\n                var a = a mod T.mod.int\n                if a < 0: a += T.mod.int\n                return T(a: a.uint32)\n    \n        proc `-`*[T: BarrettModint](a: T): T = T(a: T.umod - a.a)\n        proc `+=`*[T: BarrettModint](a: var T, b: T or SomeInteger) =\n            a.a += init(T, b).a\n            if a.a >= T.umod: a.a -= T.umod\n        proc `-=`*[T: BarrettModint](a: var T, b: T or SomeInteger) =\n            a.a -= init(T, b).a\n            if a.a >= T.umod: a.a += T.umod\n        proc `*=`*[T: BarrettModint] (a: var T, b: T or SomeInteger) =\n            a.a = rem(T, (a.a).uint * (init(T, b).a).uint)\n        proc inv*[T: BarrettModint](x: T): T =\n            assert x.val != 0\n            var x: int32 = int32(x.val)\n            var y: int32 = T.mod\n            var u = 1i32\n            var v, t = 0i32\n            while y > 0:\n                t = x div y\n                x -= t * y\n                u -= t * v\n                swap(x, y)\n                swap(u, v)\n            return init(T, u)\n        proc `/=`*[T: BarrettModint](a: var T, b: T or SomeInteger) = a *= init(T, b).inv\n        proc val*(a: BarrettModint): int = a.a.int\n        macro declarStaticBarrettModint*(name, M) =\n            let converter_name = ident(\"to\" & $`name`)\n            quote do:\n                type `name`* = StaticBarrettModint[`M`]\n                converter `converter_name`*(a: int): StaticBarrettModint[`M`] = init(StaticBarrettModint[`M`], a)\n        macro declarDynamicBarrettModint*(name, id) =\n            let converter_name = ident(\"to\" & $`name`)\n            quote do:\n                type `name`* = DynamicBarrettModint[`id`]\n                converter `converter_name`*(a: int): DynamicBarrettModint[`id`] = init(DynamicBarrettModint[`id`], a)\n    \n    when not declared CPLIB_MODINT_MODINT_MONTGOMERY:\n        const CPLIB_MODINT_MODINT_MONTGOMERY* = 1\n        import std/macros\n        type StaticMontgomeryModint*[M: static[uint32]] = object\n            a: uint32\n        type DynamicMontgomeryModint*[M: static[uint32]] = object\n            a: uint32\n        type MontgomeryModint* = StaticMontgomeryModint or DynamicMontgomeryModint\n    \n        proc get_r*(M: uint32): uint32 =\n            result = M\n            for _ in 0..<4: result *= 2u32 - M * result\n        proc get_n2*(M: uint32): uint32 = uint32((not uint(M - 1u32)) mod uint(M))\n        proc check_params(M, r: uint32) =\n            assert M < (1u32 shl 30), \"invalid mod >= 2^30\"\n            assert (M and 1u32) == 1u32, \"invalid mod % 2 == 0\"\n            assert r * M == 1, \"r * mod != 1\"\n        func get_param*[M: static[uint32]](self: typedesc[DynamicMontgomeryModint[M]]): ptr[tuple[M, r, n2: uint32]] =\n            {.cast(noSideEffect).}:\n                var p {.global.}: tuple[M, r, n2: uint32] = (998244353u32, get_r(998244353u32), get_n2(998244353u32))\n                return p.addr\n        template get_M*(T: typedesc[MontgomeryModint]): uint32 =\n            when T is StaticMontgomeryModint: T.M\n            else: (get_param(T))[].M\n        proc setMod*[T: static[uint32]](self: typedesc[DynamicMontgomeryModint[T]], M: SomeInteger or SomeUnsignedInt) =\n            var r = get_r(M.uint32)\n            var n2 = get_n2(M.uint32)\n            var p = (M.uint32, r, n2)\n            (get_param(self))[] = p\n            check_params(M.uint32, r)\n    \n        template umod*[T: MontgomeryModint](self: typedesc[T] or T): uint32 =\n            when self is typedesc:\n                when self is StaticMontgomeryModint: self.M\n                else: ((get_param(self))[]).M\n            else: T.umod\n        template `mod`*[T: MontgomeryModint](self: typedesc[T] or T): int32 = (T.umod).int32\n    \n        func reduce(T: typedesc[MontgomeryModint], b: uint): uint32 =\n            when T is StaticMontgomeryModint:\n                const r = get_r(T.M)\n                return cast[uint32]((b + uint(cast[uint32](b) * (not (r - 1u32))) * T.M) shr 32)\n            else:\n                var p = (get_param(T))[]\n                return cast[uint32]((b + uint(cast[uint32](b) * (not (p.r - 1u32))) * p.M) shr 32)\n        proc init*(T: typedesc[MontgomeryModint], a: T or SomeInteger): auto =\n            when a is T: return a\n            elif T is StaticMontgomeryModint:\n                const r = get_r(T.M)\n                const n2 = get_n2(T.M)\n                check_params(T.M, r)\n                var ai = reduce(T, uint(a.int32 mod T.M.int32 + T.M.int32) * n2)\n                result = StaticMontgomeryModint[T.M](a: ai)\n            elif T is DynamicMontgomeryModint:\n                var p = (get_param(T))[]\n                var ai = reduce(T, uint(a.int32 mod p.M.int32 + p.M.int32) * p.n2)\n                result = DynamicMontgomeryModint[T.M](a: ai)\n    \n        proc `+=`*[T: MontgomeryModint](a: var T, b: T or SomeInteger) =\n            a.a += init(T, b).a - T.get_M * 2u32\n            if cast[int32](a.a) < 0i32: a.a += T.get_M * 2u32\n        proc `-=`*[T: MontgomeryModint](a: var T, b: T or SomeInteger) =\n            a.a -= init(T, b).a\n            if cast[int32](a.a) < 0i32: a.a += T.get_M * 2u32\n        proc val*[T: MontgomeryModint](a: T): int =\n            result = reduce(T, a.a).int\n            if result.uint32 >= T.get_M: result -= T.get_M.int\n    \n        proc `-`*[T: MontgomeryModint](a: T): T = init(T, 0) - a\n        proc `*=`*[T: MontgomeryModint] (a: var T, b: T or SomeInteger) = a.a = reduce(T, uint(a.a) * init(T, b).a)\n        proc inv*[T: MontgomeryModint](x: T): T =\n            assert x.val != 0\n            var x: int32 = int32(x.val)\n            var y: int32 = T.mod\n            var u = 1i32\n            var v, t = 0i32\n            while y > 0:\n                t = x div y\n                x -= t * y\n                u -= t * v\n                swap(x, y)\n                swap(u, v)\n            return init(T, u)\n        proc `/=`*[T: MontgomeryModint](a: var T, b: T or SomeInteger) = a *= init(T, b).inv\n    \n        macro declarStaticMontgomeryModint*(name, M) =\n            let converter_name = ident(\"to\" & $`name`)\n            quote do:\n                type `name`* = StaticMontgomeryModint[`M`]\n                converter `converter_name`*(a: int): StaticMontgomeryModint[`M`] = init(StaticMontgomeryModint[`M`], a)\n        macro declarDynamicMontgomeryModint*(name, id) =\n            let converter_name = ident(\"to\" & $`name`)\n            quote do:\n                type `name`* = DynamicMontgomeryModint[`id`]\n                converter `converter_name`*(a: int): DynamicMontgomeryModint[`id`] = init(DynamicMontgomeryModint[`id`], a)\n    \n    import std/math\n    import std/algorithm\n    declarStaticMontgomeryModint(modint998244353_montgomery, 998244353u32)\n    declarStaticMontgomeryModint(modint1000000007_montgomery, 1000000007u32)\n    declarDynamicMontgomeryModint(modint_montgomery, 1u32)\n    declarStaticBarrettModint(modint998244353_barrett, 998244353u32)\n    declarStaticBarrettModint(modint1000000007_barrett, 1000000007u32)\n    declarDynamicBarrettModint(modint_barrett, 1u32)\n    func `+`*(a, b: MontgomeryModint or BarrettModint): auto = (result = a; result += b)\n    func `-`*(a, b: MontgomeryModint or BarrettModint): auto = (result = a; result -= b)\n    func `*`*(a, b: MontgomeryModint or BarrettModint): auto = (result = a; result *= b)\n    func `/`*(a, b: MontgomeryModint or BarrettModint): auto = (result = a; result /= b)\n    func `+`*(a: MontgomeryModint or BarrettModint, b: SomeInteger): auto = (result = a; result += b)\n    func `-`*(a: MontgomeryModint or BarrettModint, b: SomeInteger): auto = (result = a; result -= b)\n    func `*`*(a: MontgomeryModint or BarrettModint, b: SomeInteger): auto = (result = a; result *= b)\n    func `/`*(a: MontgomeryModint or BarrettModint, b: SomeInteger): auto = (result = a; result /= b)\n    func `+`*(a: SomeInteger, b: MontgomeryModint or BarrettModint): auto = b + a\n    func `-`*(a: SomeInteger, b: MontgomeryModint or BarrettModint): auto = b - a\n    func `*`*(a: SomeInteger, b: MontgomeryModint or BarrettModint): auto = b * a\n    func `/`*(a: SomeInteger, b: MontgomeryModint or BarrettModint): auto = b / a\n    proc `/`*[ModInt: MontgomeryModint or BarrettModint](a: ModInt, b: static int): auto =\n        const tmp = init(Modint, b).inv\n        return a * tmp\n    func pow*(a: MontgomeryModint or BarrettModint, n: int): auto =\n        result = init(typeof(a), 1)\n        var a = a\n        var n = n\n        while n > 0:\n            if (n and 1) == 1: result *= a\n            a *= a\n            n = (n shr 1)\n    func `$`*(a: MontgomeryModint or BarrettModint): string = $(a.val)\n    proc estimate_rational*(a: MontgomeryModint or BarrettModint, ub: int = isqrt(typeof(a).mod)): string =\n        var v: seq[tuple[s, n, d: int]]\n        for d in 1..ub:\n            var n = (a * d).val\n            if n * 2 > a.mod:\n                n = - (a.mod - n)\n            if gcd(n, d) > 1: continue\n            v.add((n.abs + d, n, d))\n        v.sort\n        return $v[0].n & \"/\" & $v[0].d\n"
# source: https://github.com/kemuniku/cplib/tree/main/src/cplib/math/combination.nim
ImportExpand "cplib/math/combination" <=== "when not declared CPLIB_MATH_COMBINATION:\n    const CPLIB_MATH_COMBINATION* = 1\n    type Combination_Type[ModInt] = object\n        fact: seq[ModInt]\n        inv: seq[ModInt]\n        fact_inv: seq[ModInt]\n\n    proc initCombination*[ModInt](max_N: int): Combination_Type[ModInt] =\n        var fact = newSeq[ModInt](max_N+1)\n        var inv = newSeq[ModInt](max_N+1)\n        var fact_inv = newSeq[ModInt](max_N+1)\n        fact[0] = 1\n        fact[1] = 1\n        inv[1] = 1\n        fact_inv[0] = 1\n        fact_inv[1] = 1\n        for i in 2..max_N:\n            fact[i] = fact[i-1] * i\n            inv[i] = -inv[int(ModInt.umod()) mod i]*(int(ModInt.umod()) div i)\n            fact_inv[i] = fact_inv[i-1] * inv[i]\n        result = Combination_Type[ModInt](fact: fact, inv: inv, fact_inv: fact_inv)\n\n    proc ncr*[ModInt](c: Combination_Type[ModInt], n, r: int): ModInt =\n        if n < 0 or r < 0 or n < r:\n            return 0\n        return c.fact[n]*c.fact_inv[n-r]*c.fact_inv[r]\n\n    proc npr*[ModInt](c: Combination_Type[ModInt], n, r: int): ModInt =\n        if n < 0 or r < 0 or n < r:\n            return 0\n        return c.fact[n]*c.fact_inv[n-r]\n\n    proc nhr*[ModInt](c: Combination_Type[ModInt], n, r: int): ModInt =\n        return c.ncr(n+r-1, r)\n"

{.checks: off.}
type mint = modint998244353_barrett

var h, w = input(int)
var comb = initCombination[mint](h+w)

var ans = mint(0)
var mul = mint(2).pow((h-1) * (w-1))

for i in 0..<2*h:
    var hor = (i+1) // 2
    var ver = i - hor
    ans += comb.ncr(w-1, hor) * comb.ncr(h-2, ver) * mul
    mul /= 2
print($ans)