Compilare: user.c: In function ‘read_data’: user.c:152:15: warning: unused variable ‘k’ [-Wunused-variable] int i, j, k, a, b, c; ^ user.c:152:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j, k, a, b, c; ^ user.c:154:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d\n", &N, &M, &K); ^ user.c:157:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d\n", &a, &b, &c), G[a][b] = G[b][a] = c*10; ^ user.c: In function ‘main’: user.c:170:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("trafic.in", "rt", stdin); ^ user.c:171:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("trafic.out", "wt", stdout); ^