Compilare: user.cpp: In function ‘int main()’: user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<g[i].size();j++) ^ user.cpp:9:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("itree.in","r",stdin); ^ user.cpp:10:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("itree.out","w",stdout); ^ user.cpp:12:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&tests); ^ user.cpp:14:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:19:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^