codeforces 1100C

#include<bits/stdc++.h>

using namespace std;

/// Typedef
typedef long long ll;

#define sc1(a) scanf("%lld",&a)
#define sc2(a,b) scanf("%lld %lld",&a,&b)

#define pf1(a) printf("%lld\n",a)
#define pf2(a,b) printf("%lld %lld\n",a,b)

#define mx 10000007
#define mod 100000007
#define PI acos(-1.0)

int dr[] = {-2,-2,-1,-1,1,1,2,2};
int dc[] = {-1,1,-2,2,-2,2,-1,1};


int main()
{
    ll num, m, tc = 1;

    double n, r;

    cin >> n >> r;

    double angel = sin(PI/n);

    double R = (angel * r) / (1.0 - angel);

    printf("%.7lf\n", R);

    return 0;
}