Compilare: user.cpp: In function ‘int main()’: user.cpp:31:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[i].size();++j) ^ user.cpp:16:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mayonaka.in","r",stdin); ^ user.cpp:17:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mayonaka.out","w",stdout); ^ user.cpp:19:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:23:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&A.x,&A.y,&salt,&A.g); ^