#include <fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int main ()
{
	long int a[100][100],i,j,n,m,s=0;
f>>n>>m;
for (i=1;i<=n;i++)
	for (j=1;j<=m;j++)
		f>>a[i][j];
for (i=1;i<=n;j++)
	for (j=1;j<=m;j++)
		if (a[i][j]>0)
			s=s+a[i][j];
g<<s;
return 0;
}