import sys input = sys.stdin.buffer.readline sys.setrecursionlimit(10 ** 7) inf = 10**18 N, M = map(int, input().split()) G = [[inf] * N for _ in range(N)] for _ in range(M): a, b, c = map(int, input().split()) a -= 1 b -= 1 G[a][b] = min(G[a][b], c) for i in range(N): G[i][i] = 0 for k in range(N): for i in range(N): for j in range(N): G[i][j] = min(G[i][j], G[i][k] + G[k][j]) for i in range(N): ans = 0 for j in range(N): if G[i][j] <= 10 ** 15: ans += G[i][j] print(ans)