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#include "bits/stdc++.h"
// @JASPER'S BOILERPLATE
using namespace std;
using ll = long long;
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define FORD(i, a, b) for(int i = a; i >= b; i--)
#define REP(i, b) for(int i = 0; i < b; i++)
#define PER(i, b) for(int i = b - 1; i >= 0; i--)
#define fi first
#define se second
#ifdef JASPER2
#include "debug.h"
#else
#define debug(...) 166
#endif

using pii = pair < int, int >;
const int INF = 1e9;
const int MOD = 1e9 + 7;
const int N = 1e2 + 5;

int n, m;
string s;
bool found, used[N][N];
char a[N][N];

int dx[] = {0, 0, -1, 1};
int dy[] = {-1, 1, 0, 0};

void solve(int i, int j, int pos) {
    // tai o (i, j), tai vi tri pos cua xau S;

    if (found == true || pos == (int) s.size()) {
        found = true;
        return;
    }

    for (int k = 0; k < 4; ++k) {
        int ni = i + dx[k];
        int nj = j + dy[k];
        if (1 <= ni && ni <= n && 1 <= nj && nj <= m && !used[ni][nj] && a[ni][nj] == s[pos]) {
            used[ni][nj] = 1;
            solve(ni, nj, pos + 1);
            used[ni][nj] = 0;
        }
    }
} 
void run_case() {
    cin >> n >> m;
    for (int i = 1; i <= n; ++i) 
        for (int j = 1; j <= m; ++j)
            cin >> a[i][j];

    cin >> s;

    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) {
            if (a[i][j] == s[0]) {
                used[i][j] = 1;
                solve(i, j, 1);
                used[i][j] = 0;
            }
        }
    }

    cout << (found? "YES\n" : "NO\n");

}

signed main() {
    cin.tie(0) -> sync_with_stdio(0);
    #ifdef JASPER2
        freopen("in1", "r", stdin);
    #endif

    int Test = 1;
    //cin >> Test;
    for (int test = 1; test <= Test; test++){

        run_case();
    }
}