#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 2;
int num[N] = { 0 };
string a[N];
int check(int num[], int m) {
    for (int i = 0; i < m; i++) {
        if (num[i] == 1)
            return i;
    }
    return 0;
}
int main() {
    int n;
    int m;
    cin >> n >> m;
    int result = n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        for (int j = 0; j < m; j++) {
            num[j] += a[i][j] - '0';
        }
    }
    int c;
    while (c = check()) {
        result--;
        for (int i = 0; i < n; i++) {
            if (a[i][c] == '1') {
                for (int j = 0; j < m; j++) {
                    num[j] -= a[i][j] - '0';
                    a[i][j] = '0';
                }
                break;
            }
        }
    }
    cout << result << endl;
    return 0;
}

/sandbox/1/a.cpp: In function 'int main()':
/sandbox/1/a.cpp:30:22: error: too few arguments to function 'int check(int*, int)'
     while (c = check())
                      ^
/sandbox/1/a.cpp:6:5: note: declared here
 int check(int num[],int m)
     ^~~~~