vector<string> bomberMan(int n, vector<string> grid) {
    vector<string> set1=grid, set2, set3;

    for (int i=0;i<grid.size();i++)
        for (int j=0;j<grid[0].size();j++)
            set1[i][j]='O';
    set2=set3=set1;
    for (int i=0;i<grid.size();i++)
        for (int j=0;j<grid[0].size();j++)
            if (grid[i][j]=='O')
            {
                if (i>0)    set2[i-1][j]='.';
                if (i<grid.size()-1)    set2[i+1][j]='.';
                if (j>0)    set2[i][j-1]='.';
                if (j<grid[0].size()-1) set2[i][j+1]='.';
                set2[i][j]='.';
            }
    for (int i=0;i<grid.size();i++)
        for (int j=0;j<grid[0].size();j++)
            if (set2[i][j]=='O')
            {
                if (i>0)    set3[i-1][j]='.';
                if (i<set2.size()-1)    set3[i+1][j]='.';
                if (j>0)    set3[i][j-1]='.';
                if (j<set2[0].size()-1) set3[i][j+1]='.';
                set3[i][j]='.';
            }
    /*cout << "Printing grid, set1, set2 : \n";
    for (int i=0;i<grid.size();i++) cout << grid[i] << endl;
    cout << endl << endl;
    for (int i=0;i<grid.size();i++) cout << set1[i] << endl;
    cout << endl << endl;
    for (int i=0;i<grid.size();i++) cout << set2[i] << endl;*/

    if (n%2==0) return set1;
    if (n==1) return grid;
    if (n%4==3) return set2;
    return set3;
}