Compilare: user.cpp: In function ‘void solve(std::vector<int>)’: user.cpp:56:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (ans>A.size()/2) ^ user.cpp: In function ‘void dfs(int)’: user.cpp:134:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (cheii[*i].size()>MAX) ^ user.cpp: In function ‘int main()’: user.cpp:168:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("egal.in","r",stdin); ^ user.cpp:169:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("egal.out","w",stdout); ^ user.cpp:171:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:175:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&X,&Y); ^ user.cpp:180:12: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("\n"); ^ user.cpp:181:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(str); ^ /tmp/ccDpeZ5y.o: In function `main': user.cpp:(.text.startup+0x128): warning: the `gets' function is dangerous and should not be used.