Compilare: user.cpp: In function ‘int main()’: user.cpp:20:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(long k =0;k<n;k++) ^ user.cpp:24:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(long i = a1;i<=b1;i++ ) ^ user.cpp:19:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%lu",&n); ^ user.cpp:23:35: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%lu%lu",&a1,&b1); ^