def superDigit(n, k):

str1 = str(n)
sum1 =  0

for i in str1:
    sum1 += int(i)

sum1 = sum1*k
str2 = str(sum1)

while len(str2) != 1:
    sum2 = 0
    for i in str2:
        sum2 += int(i)
    str2 = str(sum2)
return sum2