#3.17
import random
from matplotlib import pyplot as plt
a=[]
#a[0]=x1
#a[1]=y1
#a[2]=x2
#a[3]=y2
n,N=0,1000000
for _ in range (N):
    for i in range (4):
        a.append(random.uniform(-1, 1))
    if (a[0])**2 + (a[1])**2 <= 1:
        if (a[2])**2 + (a[3])**2 <= 1:
            if (((a[2] - a[0])**2 + (a[3] - a[1])**2)**(1/2))<1:
                n+=1

    a=[]

print(n/N)