Compilare: user.cpp: In function ‘int main()’: user.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<sol.size();i++) ^ user.cpp:35:32: 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:36:34: 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:38:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&M); ^ user.cpp:40:51: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&m[i].x,&m[i].y,&m[i].cost); ^