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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int H, W;
    cin >> H >> W;

    vector<string> S(H);
    for (auto &s : S) cin >> s;

    // key[i][j]:
    // 1 = horizontal clue starts here
    // 2 = vertical clue starts here
    // 3 = both
    vector<vector<int>> key(H, vector<int>(W, 0));

    for (int i = 0; i < H; ++i) {
        for (int j = 0; j < W; ++j) {
            if (S[i][j] != '.') continue;

            // Horizontal clue
            bool left_black_or_out =
                (j == 0 || S[i][j - 1] == '#');
            bool right_white =
                (j + 1 < W && S[i][j + 1] == '.');

            if (left_black_or_out && right_white) {
                key[i][j] |= 1;
            }

            // Vertical clue
            bool up_black_or_out =
                (i == 0 || S[i - 1][j] == '#');
            bool down_white =
                (i + 1 < H && S[i + 1][j] == '.');

            if (up_black_or_out && down_white) {
                key[i][j] |= 2;
            }
        }
    }

    vector<pair<int, int>> starts;

    // 上の行から、同じ行では左から順番に追加される。
    for (int i = 0; i < H; ++i) {
        for (int j = 0; j < W; ++j) {
            if (key[i][j] != 0) {
                starts.emplace_back(i, j);
            }
        }
    }

    cout << starts.size() << '\n';

    for (auto [i, j] : starts) {
        string R = "-", C = "-";

        // 横のカギ
        if (key[i][j] & 1) {
            R = "";
            int y = j;
            while (y < W && S[i][y] == '.') {
                R += 'a';
                ++y;
            }
        }

        // 縦のカギ
        if (key[i][j] & 2) {
            C = "";
            int x = i;
            while (x < H && S[x][j] == '.') {
                C += 'a';
                ++x;
            }
        }

        cout << R << ' ' << C << '\n';
    }

    return 0;
}