#!/usr/bin/env python
# -*- coding:utf-8 -*-

def main():
    # a = list(range(1000))
    # a[0] = 4.0
    # a[1] =  3.0;
    # for i in range(2, 10):
    #     a[i] = (19 * a[i-1] - 12 * a[i-2]) / 4.0
    #     print(a[i], 4.0 * (3.0 / 4.0) ** i)
    N = input()
    print(4.0 * (3.0 / 4.0) ** N)

if __name__ == "__main__":
    main()