#include<bits/stdc++.h>
#define ll long long
#define mod 998244353
#define For(i, a, n) for(int i = a; i <= n; i++)
using namespace std;
ll n,m;
long double answer;
long double pi;
void work()
{
    answer=0;
    pi=acos(-1.0);
    cin>>n>>m;
    for(ll i=1;i<=n;i++)
    {
        for(ll j=0;j<=m;j++)
        {
            long double now=0;
            for(ll k=1;k<=n;k++)
            {
                long double res=0;
                ll p=min(i,k);
                res+=i+k-p*2;
                if(j>0&&j*pi/m>2)
                {
                    res+=2.0*p;
                }
                else
                {
                    res+=1.0*j*pi*p/m;
                }
                now+=res;
            }
            if(j>=1&&j<m)answer+=2.0*now;
            else answer+=now;
        }
    }
    answer*=m;
    if(m!=1)
    for(ll i=1;i<=n;i++)answer+=2.0*m*i;
    cout<<fixed<<setprecision(10)<<answer<<'\n';
}
int main()
{
    ios::sync_with_stdio,cin.tie(0),cout.tie(0);
    ll T=1;
//    cin>>T;
    while(T--)
    {
        work();
    }
}