class Solution {
public:
    void solve(vector<vector<char>>& board) {


        if( board.empty() ) return;
        int n = (int)board.size();
        int m = (int)board[0].size();

        for(int i=0;i<n;i++)
        {
            if(board[i][0] == 'O') check( i, 0, board );
            if(board[i][m-1] == 'O') check(i, m-1, board );
        }

        for(int i=0;i<m;i++)
        {
            if(board[0][i] == 'O') check( 0, i, board );
            if(board[n-1][i] == 'O') check( n-1, i, board );
        }

        for(int i=0;i<n;i++)
        {
            for(int j=0;j<m; j++ )
            {
                auto & val = board[i][j];

                cout<<val<<" ";

                 if(val == 'O') val = 'X';
                 else if ( val =='#' ) val = 'O';
            }
            cout<<"\n";
        }

    }

    private:

    void check(int i, int j, vector<vector<char>>&g)
    {
        if( i< 0 || j < 0 || i>= (int)g.size() || j >= (int)g[0].size() )
            return ;
        if(g[i][j] != 'O') return ;
        g[i][j] = '#';

        check(i, j-1, g );
        check( i, j+1, g );
        check( i+1, j, g );
        check( i-1, j, g );
    }
};