Compilare: user.cpp: In function ‘void prim()’: user.cpp:40:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[node].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:61:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < arb.size(); i++) ^ user.cpp:50:31: 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:51:33: 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:52:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:54:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &x, &y, &z); ^