Compilare: user.cpp: In function ‘int main()’: user.cpp:31:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<list[x].size();i++){ ^ user.cpp:17:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pcb.in","r",stdin); ^ user.cpp:18:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pcb.out","w",stdout); ^ user.cpp:20:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld %ld",&n,&m,&k); ^ user.cpp:22:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld",&x,&y); ^