#10162Last Digit

Give you a integer number N (1 ≤ n ≤ 2 ∗ 10100). Please compute S = 11 + 22 + 33 + . . . + N N Give the last digit of S to me.

Input

Input file consists of several N ’s, each N a line. It is ended with N = 0.

Output

For each N give a line containing only one digit, which is the last digit of S.

1
2
3
0

1
5
2