#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <array>
#include <cstring>
#include <cstdlib>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int h, w;
    cin >> h >> w;

    vector<char> a(h * w + 1);
    for (int i = 0; i < h; i++) {
        cin >> &a[w * i];
    }

    int b = 0;

    int s = 1;
    for (int i = 0; i < h; i++) {
        int t = 0;
        for (int j = 0; j < w; j++) {
            t |= a[w * i + j] - '0' + 1;
        }
        if (t != 3) {
            s = 0;
            break;
        }
    }
    b |= s;

    s = 1;
    for (int j = 0; j < w; j++) {
        int t = 0;
        for (int i = 0; i < h; i++) {
            t |= a[w * i + j] - '0' + 1;
        }
        if (t != 3) {
            s = 0;
            break;
        }
    }
    b |= s;

    cout << (b ? "YES" : "NO") << endl;

    return 0;
}