#include using namespace std; #define inf 1000000000 #define INF 1000000000000000 #define ll long long #define ull unsigned long long #define M (int)(1e9+7) #define P pair #define PLL pair #define FOR(i,m,n) for(int i=(int)m;i<(int)n;i++) #define RFOR(i,m,n) for(int i=(int)m;i>=(int)n;i--) #define rep(i,n) FOR(i,0,n) #define rrep(i,n) RFOR(i,n,0) #define all(a) a.begin(),a.end() #define IN(a,n) rep(i,n){ cin>>a[i]; } const int vx[4] = {0,1,0,-1}; const int vy[4] = {1,0,-1,0}; #define PI 3.14159265 #define F first #define S second #define PB push_back #define EB emplace_back #define int ll void init(){ cin.tie(0); ios::sync_with_stdio(false); } double power(double x,ll k){ double ret=1; while(k>0){ if(k&1) ret*=x; x*=x; k >>= 1; } return ret; } main(){ int n; cin>>n; printf("%.10lf\n",4*power(0.75,n)); }