#include <bits/stdc++.h>
using namespace std;

#define NL '\n'
#define xx first
#define yy second
#define eps 1e-9
#define ins insert
#define pb push_back
#define mp make_pair
#define ll long long
#define sz(x) x.size()
#define pi 2.0*acos(0.0)
#define sqr(x) ((x) * 1ll * (x))
#define all(x) (x).begin(),(x).end()
#define FIN freopen("input.txt", "r", stdin);
#define FOUT freopen("output.txt", "w", stdout);
#define rep(ii,aa,bb) for(int (ii)=int(aa);(ii)<(int)(bb);++(ii))
#define per(ii,aa,bb) for(int (ii)=int(aa)-1;(ii)>=(int)(bb);--(ii))
#define _fastIO() ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0)

ll bigMod(ll N,ll P,ll M){
    //used for calculating: N^P % M
    if(P==0) return 1;
    if(P%2==0){
        ll ret=bigMod(N,P/2,M);
        return ((ret%M)*(ret%M))%M;
    }
    else return ((N%M)*(bigMod(N,P-1,M)%M))%M;
}

bool status[10000001];
void sieve(void){
  int n = sqrt(1000001);
  for(int i=3; i<=n; i+=2){
    if(status[i]==0){
      for(int j=i*i; j<1000001; j += i+i){
        status[j] = 1;
      }
    }
  }
}

int main(){
    _fastIO();
    double a , b;
    cin >> a >> b;
    double area1 = pi * a * a;
    double area2 = pi * (b-a) * (b-a);
    double toto = area1 - area2;
    cout<< fixed << setprecision(6) << (100 - toto*100/area1);
}