import std.conv, std.functional, std.range, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } string COLOR(string s = "") { return "\x1b[" ~ s ~ "m"; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } struct ModInt(uint M_) { import std.conv : to; alias M = M_; uint x; this(ModInt a) { x = a.x; } this(uint x_) { x = x_ % M; } this(ulong x_) { x = cast(uint)(x_ % M); } this(int x_) { x = ((x_ %= cast(int)(M)) < 0) ? (x_ + cast(int)(M)) : x_; } this(long x_) { x = cast(uint)(((x_ %= cast(long)(M)) < 0) ? (x_ + cast(long)(M)) : x_); } ref ModInt opAssign(T)(inout(T) a) if (is(T == uint) || is(T == ulong) || is(T == int) || is(T == long)) { return this = ModInt(a); } ref ModInt opOpAssign(string op, T)(T a) { static if (is(T == ModInt)) { static if (op == "+") { x = ((x += a.x) >= M) ? (x - M) : x; } else static if (op == "-") { x = ((x -= a.x) >= M) ? (x + M) : x; } else static if (op == "*") { x = cast(uint)((cast(ulong)(x) * a.x) % M); } else static if (op == "/") { this *= a.inv(); } else static assert(false); return this; } else static if (op == "^^") { if (a < 0) return this = inv()^^(-a); ModInt b = this, c = 1U; for (long e = a; e; e >>= 1) { if (e & 1) c *= b; b *= b; } return this = c; } else { return mixin("this " ~ op ~ "= ModInt(a)"); } } ModInt inv() const { uint a = M, b = x; int y = 0, z = 1; for (; b; ) { const q = a / b; const c = a - q * b; a = b; b = c; const w = y - cast(int)(q) * z; y = z; z = w; } assert(a == 1); return ModInt(y); } ModInt opUnary(string op)() const { static if (op == "+") { return this; } else static if (op == "-") { ModInt a; a.x = x ? (M - x) : 0U; return a; } else static assert(false); } ModInt opBinary(string op, T)(T a) const { return mixin("ModInt(this) " ~ op ~ "= a"); } ModInt opBinaryRight(string op, T)(T a) const { return mixin("ModInt(a) " ~ op ~ "= this"); } bool opCast(T: bool)() const { return (x != 0U); } string toString() const { return x.to!string; } } enum MO = 998244353; alias Mint = ModInt!MO; void main() { try { for (; ; ) { const N = readLong; const A = readLong; const K = readLong; const Q = N / (2*K); const R = N % (2*K); Mint ans; { // R + x + (2K) i (0 <= i < Q) Mint sum0, sum1, sum2; long lot; foreach_reverse (x; 1 .. 2*K + 1) { long b = A * (R + x); sum0 += Mint(b / K) * Mint(R + x); sum1 += Mint(b / K) * Mint(2*K); sum1 += Mint(2) * Mint(R + x); sum2 += Mint(2) * Mint(2*K); b %= K; { const t = min(b, lot); b -= t; lot -= t; } if (b > 0) { const q = (b + K - 1) / K; sum0 += Mint(q) * Mint(R + x); sum1 += Mint(q) * Mint(2*K); lot = K * q - b; } } ans += Mint(Q) * sum0; ans += (Mint(Q) * Mint(Q - 1) / 2) * sum1; ans += (Mint(Q) * Mint(Q - 1) * Mint(2 * Q - 1) / 6) * sum2; assert(lot == 0); } { Mint sum; long lot; foreach_reverse (x; 1 .. R + 1) { long b = A * x; debug writeln(__LINE__, ": ", x, " ", b / K); sum += Mint(b / K) * Mint(x); b %= K; { const t = min(b, lot); b -= t; lot -= t; } if (b > 0) { const q = (b + K - 1) / K; debug writeln(__LINE__, ": ", x, " ", q); sum += Mint(q) * Mint(x); lot = K * q - b; } } ans += sum; } ans *= 2; writeln(ans); } } catch (EOFException e) { } }