Sum

Time Limit: 2000/1000 MS (Java/Others)

Memory Limit: 131072/131072 K (Java/Others)

Description

Input

Output

Sample Input

2

Sample Output

2
Hint
1. For N = 2, S(1) = S(2) = 1. 2. The input file consists of multiple test cases.

Hint

zhuyuanchen520

Source

2013 Multi-University Training Contest 10

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