def number_of_ways(numbers):
    s = sum(numbers)
    if s%3 != 0:
        return 0
    s = s/3
    t = 2*s

    u,v,w = 0,0,0
    for x in numbers[:-1]:
        print( (u,v,w) )
        u += x
        if u==t:
            w+=v
        if u==s:
            v+=1

    return w

if __name__ == "__main__":
    print( number_of_ways([0]*4) )