Compilare: user.cpp: In function ‘int main()’: user.cpp:161:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(Q.size()>0)for(int i=0;i<Q.top().op.size();++i)printf("%d ",Q.top().op[i]); ^ user.cpp:113:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perspico.in","r",stdin); ^ user.cpp:114:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perspico.out","w",stdout); ^ user.cpp:115:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:121:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hd",&c.mat[i][j]); ^