Xiaoshi is silly boy, but he has a mathematical mind. Occasionally he will have some crazy idea on math problems. This time he gives out such a problem : Please work out the summation of the following formula, Sum = 1 + 2 + ... + n, which satisfies n≤10^100000.
"Don't try to do a snow job on me. I know you couldn't solve it efficiently." I say to him.
"Ah... actually the formula is Sum = 1 + 2 + 3 + ... + 10^n, which satisfies n≤100000. Then can you effectively solve it?"
Thre are multiple test cases. For each case, there is a line contains n which has been described above. (0≤n≤100000)
Input is terminated by one line contains "-1".
Output the summation corresponding to each input n.
1
2
-155
5050