escacs(2)

//by xerpi

#include <iostream>
using namespace std;



int main()
{
    int rows, columns, sum, n;
    char c;
    bool is_white, starts_white = true;
    cin >> rows >> columns;
    is_white = starts_white;
    sum = 0;
    for(int i = 0; i < rows; ++i) {
        for(int j = 0; j < columns; ++j) {
            cin >> c;
            n = c - '0';
            if(is_white) sum = sum +n;
            if (is_white) is_white = false;
            else is_white = true;
        }
        if ( starts_white)  starts_white = false;
        else  starts_white = true;
        is_white =  starts_white;
    }
    cout << sum << endl;

    return 0;
}