Description
The numbers of all offices in the new building of the Tax Office of IT City will have lucky numbers.
Lucky number is a number that 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 longer than n digits.
Input
The only line of input contains one integer n (1 ≤ n ≤ 55) — the maximum length of a number that a door-plate can hold.
Output
Output one integer — the maximum number of offices, than can have unique lucky numbers not longer than n digits.
Sample Input
2
6
#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
using namespace std;
__int64 a[60];
void dabiao()
{
int i,j;
a[1]=2;
for(i=2;i<=60;i++)
{
long long temp=1;
for(j=1;j<=i;j++)
{
temp*=2;
}
a[i]=a[i-1]+temp;
}
}
int main()
{
dabiao();
int n;
while(scanf("%d",&n)!=EOF)
{
printf("%I64d\n",a[n]);
}
}

本文介绍了一个算法,用于生成由数字7和8组成的幸运数字,并计算在限定位数内可能生成的最大数量的独特幸运数字。该算法适用于税务办公室新大楼办公室编号的需求。

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