P42280: Tauler d'escacs (1)

#include <iostream>
#include <string>
using namespace std;

int main() {
    int filas, cols, sum, i;
    cin >> filas >> cols;
    string row;
    sum = i = 0;
    while (i < filas) {
        cin >> row;
        for (int j = 0;j < cols;++j) {
            char c = row[j];
            sum += c - '0';
        }
        ++i;
    }
    cout << sum << endl;
}