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Fibonacci strings generation

Fibonacci strings generation

Time limit 1 second
Memory limit 128 MiB

Generate n-th Fibonacci string that is defined with the next recurrent formula:

  • f(0) = "a";

  • f(1) = "b";

  • f(n) = f(n - 1) + f(n - 2), where "+" operation means concatenation

For example, f(3) = f(2) + f(1) = (f(1) + f(0)) + f(1) = "b" + "a" + "b" = "bab".

Input data

One integer n~(0 \le n \le 20).

Output data

Print the n-th Fibonacci string.

Examples

Input example #1
3
Output example #1
bab
Input example #2
5
Output example #2
babbabab
Author Mykhailo Medvediev