void tryExplode(std::vector<string>& src, int i, int j){
    size_t rows = src.size();
    size_t columns = src[0].size();
    
    
    if(i < 0 || j < 0 || i >= rows || j >= columns){
        return;
    }
    
    src[i][j] = '.';


}

vector<string> makeFullGrid(size_t rows, size_t columns){
    std::string fullRow;
    fullRow.insert(0, columns, 'O');
    
    return {rows, fullRow};
    
}

std::vector<string> detonate(std::vector<string> const& src){
    size_t rows = src.size();
    size_t columns = src[0].size();
    
    auto dst = makeFullGrid(rows, columns);
    
    for(int i = 0; i < rows; ++i){
        for(int j = 0; j < columns; ++j){
            if(src[i][j] == 'O'){
                tryExplode(dst, i + 1, j);
                tryExplode(dst, i - 1, j);
                tryExplode(dst, i, j + 1);
                tryExplode(dst, i, j - 1);
                tryExplode(dst, i, j);
            }
        }
    } 
    return dst;
}



vector<string> bomberMan(int n, vector<string> grid) {

    size_t rows = grid.size();
    size_t columns = grid[0].size();
    
    if(n <= 1){
        return grid;
    }
    
    if(n%2==0){
        return makeFullGrid(rows, columns);
    }
    
    if(n%4==3){
        return detonate(grid);
     }
     
    if(n%4==1){
        auto result = detonate(grid);
        return detonate(result);
    }

    throw std::runtime_error("could not solve");
}