#include <algorithm>
#include <cmath>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using ll = long long;
#define rep(i, n) for (int i = 0; i < n; i++)
#define repk(i, k, n) for (int i = k; i < n; i++)
#define MOD 1000000007
#define INF 1e9
#define PIE 3.14159265358979323

template <class T>
inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
T GCD(T a, T b) {
    if (b == 0)
        return a;
    else
        return GCD(b, a % b);
}
template <class T>
inline T LCM(T a, T b) {
    return (a * b) / GCD(a, b);
}

using namespace std;
//#inculude <bits/stdc++.h>
#define int long long

signed main() {
    int n;
    cin >> n;
    repk(i, n, 1000) {
        string s = to_string(i);
        if (s[0] == s[1] && s[0] == s[2]) {
            cout << s << endl;
            return 0;
        }
    }
}
#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;
int main(void){
    
    int R;
    cin >> R;
    double ans = (2 * R) * acos(-1.0);
    
    cout << setprecision(20) << ans << endl;

}
