#include <bits/stdc++.h>
using namespace std;

typedef unsigned int ui;

int dr[] = {1, 0, -1, 0};
int dc[] = {0, 1, 0, -1};

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

	int rows, cols;
	string word;

	cin >> rows >> cols;

	char keyboard[rows][cols];
	int dp[rows][cols];
	memset(keyboard, 0, sizeof(keyboard));

	for (int r = 0; r < rows; r++) {
		for (int c = 0; c < cols; c++) {
			cin >> keyboard[r][c];
			dp[r][c] = -1;
		}
	}
	cin >> word;
	word += '*';

	queue<tuple<int, int, int>> q;
	q.emplace(0, 0, 0);
	ui strokesUsed = 0;
	while (!q.empty()) {
		strokesUsed++;
		ui size = q.size();
		for (ui i = 0; i < size; i++) {
			tuple<int, int, int> c = q.front();
			q.pop();
			int x = get<0>(c);
			int y = get<1>(c);
			int index = get<2>(c);
			if (dp[x][y] >= index)
				continue;
			dp[x][y] = index;
			if (keyboard[x][y] == word[index]) {
				index++;
				if (index == (int)word.size()) {
					cout << strokesUsed;
					return 0;
				}
				q.emplace(x, y, index);
				// cout << word.substr(0, index) << ' ' << x << ' ' << y << ' ' << index << ' ' << strokesUsed << " \n";
				continue;
			}
			for (int j = 0; j < 4; j++) {
				int nx = x;
				int ny = y;
				while (nx >= 0 && ny >= 0 && nx < rows && ny <= cols && keyboard[nx][ny] == keyboard[x][y]) {
					nx += dr[j];
					ny += dc[j];
				}
				if (nx < 0 || ny < 0 || nx >= rows || ny >= cols)
					continue;
				q.emplace(nx, ny, index);
			}
		}
	}
}