Compilare: user.cpp: In function ‘void solve()’: user.cpp:54:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (p=0;p<a[j].size();p++) ^ user.cpp: In function ‘void read()’: user.cpp:20:37: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d%d%d",&n,&m,&k,&q); ^ user.cpp:25:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&x,&y); ^ user.cpp: In function ‘void solve()’: user.cpp:40:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&x,&y); ^