#chuong trinh tinh so pi
import time
t1=time.time()
p=0
i=0
n=6
sohang=(-1)**i/(2*i+1)
while abs(sohang)>10**(-n):
    p += sohang
    i += 1
    sohang = (-1)**i/(2*i+1)
print(p*4)
t2=time.time()
print('Thoi gian thuc hien: {} s '.format(t2-t1))