for(int i = 1; i< grid.size()-1; i++){
        for(int j = 1; j < grid.size()-1; j++){
            if(grid[i-1][j] < grid[i][j] && grid[i][j-1] < grid[i][j] &&
               grid[i][j+1] < grid[i][j] && grid[i+1][j] < grid[i][j] ){
                grid[i][j] = 'X';
               }
        }
    }
    return grid;