Compilare: user.cpp: In function ‘int main()’: user.cpp:37:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(nrM < V.size() && M < N - 1) { ^ user.cpp:53:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < Sol.size(); i++) ^ user.cpp:17:34: 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:18:36: 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:20:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:31:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%hd", &m.x, &m.y, &m.cost); ^