Could you explain the code please? I got up to here but I dont take into account g games so not sure what Im missing as I pass the first test case but fail others.

def twoStacks(maxSum, a, b): score = 0 counter = 0

while score < maxSum:
    head_a = a[0]
    head_b = b[0]
    if head_a > head_b and (score + head_b < maxSum):
        score += head_b
        b.pop(0)
    elif head_b > head_a and (score + head_a < maxSum):
        score += head_a
        a.pop(0)
    else:
        break
    counter += 1
return counter