import std.stdio, std.array, std.string, std.conv, std.algorithm; import std.typecons, std.range, std.random, std.math, std.container; import std.numeric, std.bigint, core.bitop, std.bitmanip; void main() { immutable long MOD = 10^^9 + 7; auto s = readln.split.map!(to!int); auto N = s[0]; auto M = s[1]; auto W = readln.split.map!(to!int).array; auto G = new int[][](N); foreach (_; 0..M) { s = readln.split.map!(to!int); G[s[0]-1] ~= s[1]-1; } auto ok = new bool[][](N, N); foreach (i; 0..N) ok[i][i] = true; foreach (i; 0..N) { auto max_k = new int[](N); auto q = new BinaryHeap!(Array!(Tuple!(int, int)), "a[1] < b[1]"); q.insert(tuple(i, W[i])); while (!q.empty) { auto t = q.front; auto n = t[0]; auto k = t[1]; q.removeFront; if (k <= max_k[n]) continue; max_k[n] = k; if (k >= W[n]) ok[i][n] = true; foreach (m; G[n]) { auto nk = min(k, W[m]); if (nk <= max_k[m]) continue; q.insert(tuple(m, nk)); } } } immutable int MAX = 1001; auto modinv = new long[](MAX); modinv[0] = modinv[1] = 1; foreach(i; 2..MAX) { modinv[i] = modinv[MOD % i] * (MOD - MOD / i) % MOD; } auto f_mod = new long[](MAX); auto f_modinv = new long[](MAX); f_mod[0] = f_mod[1] = 1; f_modinv[0] = f_modinv[1] = 1; foreach(i; 2..MAX) { f_mod[i] = (i * f_mod[i-1]) % MOD; f_modinv[i] = (modinv[i] * f_modinv[i-1]) % MOD; } long comb(int n, int k) { return f_mod[n] * f_modinv[n-k] % MOD * f_modinv[k] % MOD; } long ans = 0; foreach (i; 0..N) { foreach (j; 0..N) { if (ok[i][j]) { foreach (k; 1..W[j]+1) { long tmp = (W[j] - k) % 2 == 0 ? 1 : -1;; tmp = tmp * powmod(k, W[i], MOD) % MOD; tmp = tmp * comb(W[j], k) % MOD; ans = ((ans + tmp) % MOD + MOD) % MOD; } } } } ans.writeln; } long powmod(long a, long x, long m) { long ret = 1; while (x) { if (x % 2) ret = ret * a % m; a = a * a % m; x /= 2; } return ret; }