#include<iostream>
#include <bits/stdc++.h>

#define ld long double
#define ll long long
#define rep(i, a, b) for(int i = a ; i < b ; i ++)
#define sz(v) (int)v.size()
#define all(v) begin(v), end(v)
#define IO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int N = 55;
int n, m;
char a[N][N];

int dis[10005][N][N];
int nxt[N][N][4];

void preprocess() {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            nxt[i][j][0] = j;
            while (a[i][nxt[i][j][0]] == a[i][j] && nxt[i][j][0] < m)nxt[i][j][0]++;

            nxt[i][j][1] = j;
            while (a[i][nxt[i][j][1]] == a[i][j] && nxt[i][j][1] >= 0)nxt[i][j][1]--;


            nxt[i][j][2] = i;
            while (a[nxt[i][j][2]][j] == a[i][j] && nxt[i][j][2] < n)nxt[i][j][2]++;

            nxt[i][j][3] = i;
            while (a[nxt[i][j][3]][j] == a[i][j] && nxt[i][j][3] >= 0)nxt[i][j][3]--;

            if (nxt[i][j][0] == m)nxt[i][j][0] = -1;
            if (nxt[i][j][2] == n)nxt[i][j][2] = -1;

        }
    }
}

void doWork() {
    cin >> n >> m;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    preprocess();

    string s;
    cin >> s;
    s = s + '*';

    queue<vector<int> > q;
    q.push({0, 0, 0});
    memset(dis, -1, sizeof dis);
    while (!q.empty()) {
        int idx = q.front()[0], x = q.front()[1], y = q.front()[2];
        if (idx == s.size()) {
            cout << dis[idx][x][y] + 1;
            return;
        }
        q.pop();
        if (s[idx] == a[x][y] && dis[idx + 1][x][y] == -1) {
            dis[idx + 1][x][y] = dis[idx][x][y] + 1;
            q.push({idx + 1, x, y});
        }
        for (int i = 0; i < 4; i++) {
            if (nxt[x][y][i] != -1) {
                int nxt_x = i < 2 ? x : nxt[x][y][i];
                int nxt_y = i < 2 ? nxt[x][y][i] : y;
                if (dis[idx][nxt_x][nxt_y] == -1) {
                    dis[idx][nxt_x][nxt_y] = dis[idx][x][y] + 1;
                    q.push({idx, nxt_x, nxt_y});
                }
            }
        }

    }
    assert(false);
}

int main() {
//    IO

    int t = 1;
//    cin >> t;
    for (int i = 1; i <= t; i++) {
        //  cout << "Case #" << i << ": ";
        doWork();
    }
}