#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000003
#define INF 10000000
#define LLINF 2000000000000000000LL

#define SIZE 10000

int main(){
    double a[101];
    int n;
    
    scanf("%d",&n);
    
    a[0]=4;
    a[1]=3;
    
    
    for(int i=2;i<=n;i++){
        a[i]=a[i-1]*3.0/4.0;
        
        fprintf(stderr,"%d : %.11lf\n",i,a[i]);
    }
    
    printf("%.11lf\n",a[n]);
    
    return 0;
}