//
// Stvoreno ENERGom o 09.04.24. 13:11:02
//

#include<bits/stdc++.h>

#define all(a) a.begin(),a.end()
#define len(a) (int)(a.size())
#define mp make_pair
#define MP make_pair
#define pb push_back
#define PB push_back
#define F first
#define fir first
#define S second
#define sec second

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;

#ifdef Energy
#define DEBUG for (int ____DEBUG=1;____DEBUG;____DEBUG=0)

template<class ...Ts>
auto &PRNT(Ts ...ts) { return ((cerr << ts << " "), ...); }

#define LOG(...) PRNT(#__VA_ARGS__" ::",__VA_ARGS__)<<endl
#else
#define DEBUG while(0)
#define LOG(...)
#endif

const int max_n = 52, inf = 1000111222;
const int max_len = 10011;
const int max_v = max_n * max_n;
const int dx[] = {-1, 1, 0, 0};
const int dy[] = {0, 0, -1, 1};

int n, m, dist[max_v][max_len];
string a[max_n], s, t;
vector<int> g[max_v];

bool is_in(int x, int y) {
    return 0 <= x && 0 <= y && x < n && y < m;
}

int get_num(int x, int y) {
    return x * m + y;
}

void add_edge(int i, int j, int x, int y) {
    int u = get_num(i, j), v = get_num(x, y);
    g[u].push_back(v);
}


queue<pair<int, int>> q;

void upd(int v, int c, int d) {
    if (dist[v][c] == -1) {
        dist[v][c] = d;
        q.push({v, c});
    }
}

int main() {
//    freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    cin >> s;
    s += '*';
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            t += a[i][j];
            for (int k = 0; k < 4; ++k) {
                int x = i + dx[k], y = j + dy[k];
                while (is_in(x, y) && a[x][y] == a[i][j]) {
                    x += dx[k];
                    y += dy[k];
                }
                if (!is_in(x, y)) {
                    continue;
                }
                add_edge(i, j, x, y);
            }
        }
    }
    ::memset(dist, -1, sizeof(dist));
    dist[get_num(0, 0)][0] = 0;
    q.push({get_num(0, 0), 0});
    while (!q.empty()) {
        auto [v, c] = q.front();
        q.pop();
        if (c == s.size()) {
            cout << dist[v][c] << "\n";
            exit(0);
        }
        if (t[v] == s[c]) {
            upd(v, c + 1, dist[v][c] + 1);
        }
        for (int to : g[v]) {
            upd(to, c, dist[v][c] + 1);
        }
    }
    exit(0);
}