#include<fstream.h>

int main()
{
	long int a[16][16],i,j,n,m,s=0;
	ifstream in("flip.in");
	ofstream out("flip.out");
	in>>n;in>>m;
	for (i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			in>>a[i][j];
	
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			if(a[i][j]>0) s=s+a[i][j];
	out<<s;
	in.close();
	out.close();
	return 0;
}