Compilare: user.cpp: In function ‘int main()’: user.cpp:76:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol.size(); ++i) { ^ user.cpp:48:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in", "r", stdin); ^ user.cpp:49:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out", "w", stdout); ^ user.cpp:52:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:55:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &e.u, &e.v, &e.cost); ^