// URL: https://yukicoder.me/problems/no/695 import std.algorithm, std.array, std.container, std.math, std.range, std.typecons, std.string; import std.bigint; const mod1 = 168647939L, mod2 = 592951213L, mod = mod1*mod2; version(unittest) {} else void main() { int n, m; io.getV(n, m); int[] x; io.getA(m, x); auto n2 = (n+1)/2, c = new uint[](n2); auto calc(int mod) { c[] = 0; c[0] = 1; foreach (i; 1..n2) foreach (j; 0..m) if (i >= x[j]) (c[i] += c[i-x[j]]) %= mod; auto r = 0uL; foreach (j; 0..m) foreach (i; max(0, n2-x[j])..min(n-x[j], n2)) (r += cast(ulong)c[i]*c[n-1-(i+x[j])]) %= mod; return cast(long)r; } auto r1 = BigInt(calc(mod1)), r2 = BigInt(calc(mod2)); long a, b; extGcd(mod1, mod2, a, b); io.put(((r1*b*mod2+r2*a*mod1)%mod+mod)%mod); } pure T isqrt(T)(T n) { static if (is(T == int)) auto max = 46341; else static if (is(T == long)) auto max = 3037000500L; auto bs = iota(T(0), max).map!(x => tuple(x, x^^2)).assumeSorted!"a[1]<=b[1]"; return bs.lowerBound(tuple(0, n)).back[0]; } pure T icbrt(T)(T n) { static if (is(T == int)) auto max = 1291; else static if (is(T == long)) auto max = 2097152L; auto bs = iota(T(0), max).map!(x => tuple(x, x^^3)).assumeSorted!"a[1]<=b[1]"; return bs.lowerBound(tuple(0, n)).back[0]; } pure T powr(alias pred = "a*b", T, U)(T a, U n, T one) { import std.functional; alias predFun = binaryFun!pred; if (n == 0) return one; auto r = one; for (; n > 0; n >>= 1) { if (n&1) r = predFun(r, a); a = predFun(a, a); } return r; } pure T powr(alias pred = "a*b", T, U)(T a, U n) { return powr!(pred, T, U)(a, n, T(1)); } pure T extGcd(T)(T a, T b, out T x, out T y) { auto g = a; x = 1; y = 0; if (b) { g = extGcd(b, a%b, y, x); y -= a/b*x; } return g; } auto io = IO!()(); import std.stdio; struct IO(string floatFormat = "%.10f", string delimiter = " ", alias IN = stdin, alias OUT = stdout) { import std.conv, std.format, std.meta, std.traits; auto getV(T...)(ref T v) { foreach (ref w; v) get(w); } auto getA(T)(size_t n, ref T v) if (hasAssignableElements!T) { v = new T(n); foreach (ref w; v) get(w); } auto getC(T...)(size_t n, ref T v) if (allSatisfy!(hasAssignableElements, T)) { foreach (ref w; v) w = new typeof(w)(n); foreach (i; 0..n) foreach (ref w; v) get(w[i]); } auto getM(T)(size_t r, size_t c, ref T v) if (hasAssignableElements!T && hasAssignableElements!(ElementType!T)) { v = new T(r); foreach (ref w; v) getA(c, w); } template getS(E...) { auto getS(T)(size_t n, ref T v) { v = new T(n); foreach (ref w; v) foreach (e; E) mixin("get(w."~e~");"); } } auto put(bool flush = false, T...)(T v) { foreach (i, w; v) { putA(w); if (i < v.length-1) OUT.write(delimiter); } OUT.writeln; static if (flush) OUT.flush(); } auto putB(S, T)(bool c, S t, T f) { if (c) put(t); else put(f); } auto putRaw(T...)(T v) { OUT.write(v); OUT.writeln; } private { dchar[] buf; auto sp = (new dchar[](0)).splitter; void nextLine() { IN.readln(buf); sp = buf.splitter; } auto get(T)(ref T v) { if (sp.empty) nextLine(); v = sp.front.to!T; sp.popFront(); } auto putR(T)(T v) { auto w = v; while (!w.empty) { putA(w.front); w.popFront(); if (!w.empty) OUT.write(delimiter); } } auto putA(T)(T v) { static if (isInputRange!T && !isSomeString!T) putR(v); else if (isFloatingPoint!T) OUT.write(format(floatFormat, v)); else OUT.write(v); } } }