Compilare: main.cpp: In function 'int main()': main.cpp:41:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < grafo[i].size(); j++) ~~^~~~~~~~~~~~~~~~~ main.cpp:49:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < grafo[i].size(); j++) ~~^~~~~~~~~~~~~~~~~ main.cpp:59:6: warning: unused variable 'ans' [-Wunused-variable] ll ans = 0; ^~~ main.cpp:22:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arb3.in", "r", stdin); ^ main.cpp:23:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arb3.out", "w", stdout); ^ main.cpp:26:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &q); ^ main.cpp:29:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &pai[i]); ^ main.cpp:32:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i]); ^ main.cpp:57:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %lld", &u, &k); ^