#include <iostream>

#include <fstream>

using namespace std;

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