#include <bits/stdc++.h>
using namespace std;
int r, c, visited[21][21], ret = 1, y, x, cnt[26];
int dy[] = {-1, 0, 1, 0};
int dx[] = {0, 1, 0, -1};
char a[21][21];
queue<pair<int, int>> q;
int main(){
    cin >> r >> c;
    for(int i = 0; i < r; i++){
        for(int j = 0; j < c; j++){
            cin >> a[i][j];
        }
    }
    q.push({0, 0});
    visited[0][0] = 1;
    cnt[a[0][0] - 'a']++;
    while(q.size()){
        tie(y, x) = q.front();
        q.pop();
        for(int i = 0; i < 4; i++){
            int ny = dy[i] + y;
            int nx = dx[i] + x;
            if(ny < 0 || ny >= r || nx < 0 || nx >= c || visited[ny][nx] || cnt[a[ny][nx] - 'a']) continue;
            visited[ny][nx] = visited[y][x] + 1;
            ret = max(ret, visited[ny][nx]);
            cout << ny << ' ' << nx << '\n';
            q.push({ny, nx});
        }
    }
    cout << ret << '\n';
}

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