HDU-2013 蟠桃记

#include <bits/stdc++.h>
#define pb push_back
#define _for(i,a,b) for(int i = (a);i < (b);i ++)
#define INF 0x3f3f3f3f

using namespace std;

const int maxn = 5003;

int main()
{
    int N;
    int tol;
    while(~scanf("%d",&N))
    {
        tol = 1;
        N--;
        while(N--)
            tol=(tol+1)*2;
        cout << tol << endl;
    }
    return 0; 
}