#include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long int ll; typedef unsigned long long int llu; typedef pair pii; typedef vector vi; typedef vector > vii; #define rrep(i, m, n) for(int i=m; i=m; i--) #define erev(i, n) for(int i=n; i>=1; i--) #define rev(i, n) for(int i=n-1; i>=0; i--) #define EACH(v) (v).begin(), (v).end() #define CNT(a, n, x) (upper_bound(a, a+n, x)-lower_bound(a, a+n, x)) #define minup(m, x) (m=min(m, x)) #define maxup(m, x) (m=max(m, x)) #define INF 1000000000 #define MOD 1000000009 #define EPS 1E-8 int n; double res; int main() { cin >> n; res = 4; rep(i, n) res *= 3.0 / 4.0; printf("%.20f\n", res); return 0; }