Compilare: user.cpp: In function ‘void solve(int, int)’: user.cpp:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[nod].size();i++) cnt[v[nod][i]]++; ~^~~~~~~~~~~~~~ user.cpp:23:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[nod].size();i++) cnt[v[nod][i]]--; ~^~~~~~~~~~~~~~ user.cpp: In function ‘void backk(int, int, int)’: user.cpp:35:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[nod].size();i++) cnt[v[nod][i]]++; ~^~~~~~~~~~~~~~ user.cpp:37:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[nod].size();i++) cnt[v[nod][i]]--; ~^~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:44:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alianta.in","r",stdin); ^ user.cpp:45:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alianta.out","w",stdout); ^ user.cpp:47:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&t); ^ user.cpp:50:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:53:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^