Compilare: user.cpp: In function ‘void solve()’: user.cpp:57:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<G[w.x].size();i++) ^ user.cpp: In function ‘void reload()’: user.cpp:80:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<a[w.x].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:118:16: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(In); ^ user.cpp:119:17: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(Out); ^ user.cpp:120:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&k); ^ user.cpp:122:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^