#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
#define sz(s) (int)(s).size()
#define all(s) s.begin(),s.end()

void Speed() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
}

void solve() {
    int n, m, k; cin >> n >> m >> k;
    string s, t; cin >> s;
    vector<int> mx(n), cnt(n + 1);
    for(int i = 0; i < m; i++){
        cin >> t;
        assert(sz(t) == n);
        for(int j = n - 1; j >= 0; j--){
            cnt[j] = 0;
            if(t[j] == s[j]) cnt[j] = 1 + cnt[j + 1];
            if(cnt[j] >= k) mx[j] = max(mx[j], cnt[j]);
        }
    }

    vector<int> dp(n + 1);
    dp[n] = 1;
    for(int i = n - 1; i >= 0; i--){
        for(int len = k; len <= mx[i]; len++){
            dp[i] |= dp[i + len];
        }
    }
    cout << (dp[0] ? "YES\n" : "NO\n");
}

int main() {
    freopen("killua.in", "r", stdin);
    Speed();
    int tc = 1;
    //cin >> tc;
    while (tc--) {
        solve();
    }
    return 0;
}