Compilare: user.cpp: In function ‘void solve()’: user.cpp:34:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(h=0;h<G[x].size();++h) ^ user.cpp: In function ‘void read()’: user.cpp:12:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbpal.in","r",stdin); scanf("%d\n",&n); ^ user.cpp:12:49: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbpal.in","r",stdin); scanf("%d\n",&n); ^ user.cpp:15:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&x,&y); ^ user.cpp:20:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c ",&ch[i]); ^ user.cpp: In function ‘void write()’: user.cpp:55:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbpal.out","w",stdout); printf("%d",sol); fclose(stdout); ^