#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=144494;
ll mod=1000000007;
int main(){
    ld ans=4.0*pie;
    ld a,b;
    cin >> a >> b;
    if (a>b)
    {
        swap(a,b);
    }
    if (a>=0)
    {
        ans-=2.0*pie;
        ans-=2.0*pie*(1.0-a);
        ld x=2.0*pie;
        x-=ans;
        x-=2.0*pie*(1.0-b);
        cout << setprecision(100) << x << endl;
    }else{
        if (b<=0)
        {
            ans-=2.0*pie;
            ans-=2.0*pie*(1.0+b);
            ld x=2.0*pie;
            x-=ans;
            x-=2.0*pie*(1.0+a);
            cout << setprecision(100) << x << endl;
        }else{
            ans-=2.0*(1.0+a)*pie;
            ans-=2.0*(1.0-b)*pie;
            cout << setprecision(100) << ans << endl;
        }
    }
    
}