Compilare: user.cpp: In function ‘int main()’: user.cpp:30:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[var].size();i++) ^ user.cpp:15:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&n,&m); ^ user.cpp:19:34: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&x1,&x2); ^