import numpy as np
import random

def coin_flip_head_streak():
    streaklist = []
    streak = 0
    for i in range(100):
        rand = random.randint(0,1)
        if(rand == 1):
            streak += 1
        else:
            if streak:
                streaklist.append(streak)
            streak = 0
    return np.max(streaklist)

count = 0
for i in range (10000):
    while coin_flip_head_streak() < 7:
        count += 1
print(count/10000)