#include<iostream>

#include<cstdio>

#include<algorithm>

#include<cstdlib>

#include<cstring>

#include<string>

#include<cmath>

#include<map>

#include<set>

#include<vector>

#include<queue>

#include<bitset>

#include<ctime>

#include<deque>

#include<stack>

#include<functional>

#include<sstream>

//#include<cctype>

//#pragma GCC optimize(2)

using namespace std;

#define maxn 1000005

#define inf 0x7fffffff

//#define INF 1e18

#define rdint(x) scanf("%d",&x)

#define rdllt(x) scanf("%lld",&x)

#define rdult(x) scanf("%lu",&x)

#define rdlf(x) scanf("%lf",&x)

#define rdstr(x) scanf("%s",x)

typedef long long  ll;

typedef unsigned long long ull;

typedef unsigned int U;

#define ms(x) memset((x),0,sizeof(x))

const long long int mod = 1e9 + 7;

#define Mod 1000000000

#define sq(x) (x)*(x)

#define eps 1e-4

typedef pair<int, int> pii;

#define pi acos(-1.0)

//const int N = 1005;

#define REP(i,n) for(int i=0;i<(n);i++)

typedef pair<int, int> pii;

inline ll rd() {

    ll x = 0;

    char c = getchar();

    bool f = false;

    while (!isdigit(c)) {

        if (c == '-') f = true;

        c = getchar();

    }

    while (isdigit(c)) {

        x = (x << 1) + (x << 3) + (c ^ 48);

        c = getchar();

    }

    return f ? -x : x;

}

ll gcd(ll a, ll b) {

    return b == 0 ? a : gcd(b, a%b);

}

int sqr(int x) { return x * x; }

/*ll ans;

ll exgcd(ll a, ll b, ll &x, ll &y) {

    if (!b) {

        x = 1; y = 0; return a;

    }

    ans = exgcd(b, a%b, x, y);

    ll t = x; x = y; y = t - a / b * y;

    return ans;

}

*/

int n;

double ans;

int main() {

    //ios::sync_with_stdio(0);

    cin >> n;

    if (n == 1) {

        ans = 4200 * 100.0;

        printf("%.2lf\n", 1.0*ans);

        return 0;

    }

    ans += 4200 * 100.0 / n;

    double t = 1.0;

    double cost = 4200 * 100.0 / n;

    for (int i = 2; i <= n; i++) {

        t = t * (1 - 0.5 / ((i - 1)));

        ans += t * cost*1.0;

    }

    printf("%.2lf\n", 1.0*ans);

}