#include<stdio.h>
#include<stdlib.h>
#include<math.h>
short n,m,i,j; long s,a[100][16];
int main()
{
    FILE*f=fopen("flip.in","r");
    FILE*g=fopen("flip.out","w");
    fscanf(f,"%hd %hd",&n,&m);
    for(i=0;i<n;i++)
        for(j=0;j<m;j++)
    {
        fscanf(f,"%ld",&a[i][j]);
        if(a[i][j]>0) s+=a[i][j];
    }
    fprintf(g,"%ld",s);
    fclose(f);
    fclose(g);
    return 0;
}