#include #define FOR(i,a,b) for (int i=(a);i<(b);i++) #define FORR(i,a,b) for (int i=(a);i>=(b);i--) #define pb push_back #define pcnt __builtin_popcount #define show(x) cout<<#x<<" = "< pii; typedef vector vi; typedef vector vvi; typedef vector vpii; typedef set si; typedef pair pll; typedef vector vl; typedef vector vvl; typedef vector vpll; typedef set sl; templatestring join(vector&v) {stringstream s;FOR(i,0,sz(v))s<<' '<b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;} int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;} void dout(double d){printf("%.12f\n",d);} const int iinf = 1e9; const ll linf = 1e18; const int mod = 1e9+7; const double eps = 1e-10; double dp[220][2], d[2]; int k; main(){ cin.tie(0); ios::sync_with_stdio(false); cin >> k; dp[k][0] = 0.0; dp[k][1] = 0.0; FOR(i, 1, 6){ dp[k+i][0] = 0.0; dp[k+i][1] = 1.0; } FORR(i, k-1, 0){ dp[i][0] = 1.0; dp[i][1] = 0.0; FOR(j, 1, 7){ FOR(k, 0, 2){ dp[i][k] += dp[i+j][k] / 6; } } } dout(dp[0][0] / (1.0 - dp[0][1])); }