#include <bits/stdc++.h>
using namespace std;
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int r, c;
    if (!(cin >> r >> c)) return 0;
    vector<int> base(r, 0);
    for (int i = 0; i < r; ++i) {
        string s; cin >> s;
        for (int j = 0; j < c; ++j)
            if (s[j] == 'X') base[i] |= (1 << j); // đen = 1
    }
 
    int FULL = (1 << c) - 1;
    auto pop = [](int x){ return __builtin_popcount((unsigned)x); };
 
    long long best = LLONG_MAX;
    for (int first = 0; first < (1<<c); ++first) {
        vector<int> row = base;        // copy bàn
        long long taps = 0;
        auto pressRow = [&](int i, int mask){
            if (!mask) return;
            taps += pop(mask);
            int left = (mask << 1) & FULL;
            int right = (mask >> 1);
            row[i] ^= mask ^ left ^ right;     // chính nó + trái + phải
            if (i > 0) row[i-1] ^= mask;       // trên
            if (i+1 < r) row[i+1] ^= mask;     // dưới
        };
 
        // áp dụng hàng 1
        pressRow(0, first);
 
        // quyết định các hàng tiếp theo theo trạng thái hàng trên
        for (int i = 1; i < r; ++i) {
            int mustPress = row[i-1]; // ô nào còn đen ở trên thì phải bấm ngay dưới
            pressRow(i, mustPress);
        }
 
        if (row[r-1] == 0) best = min(best, taps); // thành công nếu hàng cuối trắng hết
    }
 
    if (best == LLONG_MAX) {
        cout << "Damaged billboard.\n";
    } else {
        cout << "You have to tap " << best << " tiles.\n";
    }
    return 0;
}

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