def hourglassSum(a):
    ma = -float('inf')
    for i in range(1,5):
        for j in range(1,5):
            top = bottom = 0
            for dy in [-1,0,1] :
                top += a[i-1][j+dy]
                bottom += a[i+1][j+dy]
            ma = max(ma,top + a[i][j] + bottom)
    return ma