A cryptography class numbers its practice keys using the first few prime numbers. Given an integer K, the instructor wants the sum of the first K primes (2, 3, 5, 7, 11, ... in increasing order) to use as a checksum.
Input format
Line 1: a single integer K.
Output format
A single integer: the sum of the first K prime numbers.
Constraints
- 1 <= K <= 500