#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <cstring>
#include <numeric>
#include <algorithm>
#include <functional>
#include <array>
#include <map>
#include <queue>
#include <limits.h>
#include <set>
#include <bitset>
#include <stack>
#include <cstdlib>
#include <complex>
#include <unordered_map>
#define REP(i,n) for(int i = 0; n > i; i++)
#define MODU 33
#define Range(x,a,b) ((a) <= (x) && (x) <= (b))
#define POWT(x) ((x)*(x))
#define ALL(x) (x).begin(), (x).end()
#define C_D(c) ((c) - '0')
#define D_C(d) ((d) + '0')
using namespace std;
typedef vector<int> Ivec;
typedef pair<int, int> pii;
typedef long long int ll;

int main() {
	int n;
	char d[1000] = { "1998979695949392919099888786858483828180897877767574737271707968676665646362616069585756555453525150594847464544434241404938373635343332313039282726252423222120291817161514131211101987654321" };
	int an[1000] = {};
	scanf("%d", &n);

	REP(i, 200) {
		if (!d[i])continue;
		an[i] += (C_D(d[i]) * n);
	}
	REP(i, 200) {
		if (an[i] >= 10) {
			an[i + 1] += an[i] / 10;
			an[i] = an[i] % 10;
		}
	}
	bool f = 0;
	for (int i = 200; 189 < i; i--) {
		f = an[i];
		if (f) {
			printf("%d", an[i]);
		}
	}
	if (!f)printf("0");
	printf(".");
	for(int i = 189; 0 <= i; i--) {
		printf("%d", an[i]);
	}
	printf("\n");
	return 0;
}