python求助

def main():
    global n,k,summ,num,rest,a
    summ=0
    num=0
    rest=0
    n, k = map(int, input().split())
    summ=summ+n
    num=num+n
    a=num/k
    while(a>0):
            summ=summ+num/k
            rest=num%k
            num=num/k
            num=num+rest
            rest=0
            a=num/k
    print(summ)
main()