#include "stdio.h"
int main()
{
    int n,m;
    scanf("%d %d",&n,&m);
    int ** a = new int*[n];
    for(int i = 0; i < n; i++)
    {
        a[i] = new int[m];
    }
    
    int sum(0);
    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < m; j++)
        {
            scanf("%d",&a[i][j]);
            if(a[i][j] > 0)
            {
                sum += a[i][j];
            }
        }
    }
    
    printf("%d",sum);
    for(int i = 0; i < n; i++)
    {
        delete [] a[i];
    }
    delete [] a;
    
    return 0;
}