import std, core.bitop;
bool chmin(T)(ref T SE, T MI) { if (SE > MI) { SE = MI; return true; } else { return false; } }
bool chmax(T)(ref T SE, T MI) { if (SE < MI) { SE = MI; return true; } else { return false; } }
int lowerBound(T)(T[] SE, T MI) { int lo = -1, hi = cast(int)(SE.length); while (hi - lo > 1) { int mid = lo + hi >> 1; (SE[mid] < MI ? lo : hi) = mid; } return hi; }
int upperBound(T)(T[] SE, T MI) { int lo = -1, hi = cast(int)(SE.length); while (hi - lo > 1) { int mid = lo + hi >> 1; (SE[mid] > MI ? hi : lo) = mid; } return hi; }
void main() {
	int N, M;
	readf("%s %s\n", N, M);
	auto A = readln.chomp.split.to!(int[]);
	auto a = new int[M];
	auto b = new int[M];
	auto c = new int[M];
	auto G = new int[][](N, 0);
	foreach (i; 0 .. M) {
		readf("%s %s %s\n", a[i], b[i], c[i]);
		--a[i];
		--b[i];
		G[a[i]] ~= i;
	}
	auto dist = new long[N];
	dist[] = long.min;
	dist[0] = A[0];
	foreach (i; 0 .. N * 3) {
		bool se = false;
		foreach (u; 0 .. N) {
			foreach (j; G[u]) {
				int v = u ^ a[j] ^ b[j];
				if (chmax(dist[v], dist[u] + A[v] - c[j])) {
					if (v == N - 1) {
						se = true;
					}
				}
			}
		}
		if (i > N && se) {
			"inf".writeln;
			return;
		}
	}
	dist[N - 1].writeln;
}