#include <fstream>
#include <iostream>
#include <sstream>
#include <unistd.h>


using namespace std;
ostream& printpgm(ostream& os, int xsize, int ysize, const double * const * matrix){
	if (!os)
		return os;
	os<< "P5" << endl <<  xsize << endl << ysize << endl << 255 << endl;
        for (int y=ysize-1; y>=0; y--){
                for (int x=0;x<xsize; x++){
			unsigned char c=(unsigned char)(255*fabs(1.-matrix[x][y]));
			os.put(c);
		}
        }
	return os;
}
