Compilare: user.cpp: In function ‘bool good(int)’: user.cpp:27:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<g[b][i].second.size();j++) { ^ user.cpp: In function ‘int main()’: user.cpp:42:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("banana.in","r",stdin); ^ user.cpp:43:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("banana.out","w",stdout); ^ user.cpp:44:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&kk); ^ user.cpp:46:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); t[i].x=x; t[i].y=y; add_inhash(x,y,i); ^