Compilare: user.cpp: In function ‘int main()’: user.cpp:24:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int step=1;step<=N;step++) ^ user.cpp:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=N;i++) ^ user.cpp:41:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1;j<=N;j++) ^ user.cpp:46:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=N*N;i++) ^ user.cpp:21:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%llu",&N); ^