Compilare: main.cpp: In function 'int main()': main.cpp:35:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(val<=d[piece].size()) d[piece].insert(it,i); ~~~^~~~~~~~~~~~~~~~~ main.cpp:22:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("schi.in","r",stdin); ^ main.cpp:23:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("schi.out","w",stdout); ^ main.cpp:25:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ main.cpp:29:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&val); ^