Experimental educational round:volbit formulas Blitz C

Description

The numbers of offices in the new building of the Office of the IT city would have lucky numbers.

Lucky number is a number, consists of digits 7 and 8 only. Find the maximum number of offices in the new building of the tax Office given that a door-plate can hold a number not Lon GER than n digits.

Input

The only line of input contains one integer n (1≤ n ≤55)-the Maximum length of a number t Hat a door-plate can hold.

Output

Output one integer-the maximum number of offices, than can has unique lucky numbers not longer than n Digi Ts.

Examples input

2

Output

6
1-digit, 7 8
2-digit, 77 78 87 88
3-digit, 777 778 787 788 877 878 887 888
.....

#include <stdio.h>//#include <bits/stdc++.h> #include <string.h> #include <iostream> #include <math.h> #include <sstream> #include <set> #include <queue> #include <map> #include < vector> #include <algorithm> #include <limits.h> #define INF 0x7fffffff#define inf 0x7fffffffffffffff# Define Lson l,m,rt<<1#define Rson m+1,r,rt<<1|1#define LL long long#define ULL unsigned long longusing Namespa CE std; ll  Powl (ll X, ll N) {    ll pw = 1;    while (n > 0)    {        if (N & 1)        //N & 1 equivalent to (n% 2) = = 1            pw *= x;        x *= x;        n >>= 1;        N >>= 1 equivalent to n/= 2    }    return PW; int main () {    LL n;    LL num;    cin>>n;    Cout<<powl (2,n+1) -2<<endl;   printf ("%.20f\n", N*powl (1.000000011,num));    return 0;}

　　

Experimental educational round:volbit formulas Blitz C