#include <bits/stdc++.h>

#define ff first
#define ss second
#define mp make_pair

using namespace std;

typedef long long ll;

char mat[1005][1005];
int dist[1005][1005];
int n,m;
int row[4] = {0,1,0,-1};
int col[4] = {1,0,-1,0};

char bfs(pair<int,int> s) {
    for(int i = 0; i < n; i++)
        for(int j = 0; j < m; j++)
            dist[i][j] = -1;

    queue<pair<int,int>> Q;
    Q.push(s);
    dist[s.ff][s.ss] = 0;
    while(!Q.empty()) {
        auto x = Q.front();
        Q.pop();
        if(mat[x.ff][x.ss] >= 'a' and mat[x.ff][x.ss])
            return dist[x.ff][x.ss];

        for(int k = 0; k < 4; k++) {
            int i = row[k] + x.ff;
            int j = col[k] + x.ss;
            if(i < 0 or i >= n or j < 0 or j >= m or mat[i][j] == '#' or dist[i][j] != -1)
                continue;
            dist[i][j] = dist[x.ff][x.ss]+1;
            Q.push(mp(i,j));
        }
    }

    return -1;
}

int main(){
    pair<int,int> st;
    scanf("%d%d", &n, &m);

    for(int i = 0; i < n; i++) {
        scanf(" %s", mat[i]);
        for(int j = 0; j < m; j++) {
            if(mat[i][j] == '*')
                st = mp(i,j);
        }
    }

    printf("%d\n", bfs(st));

    return 0;
}