# -*- coding: utf-8 -*-
"""
Created on Sat Sep 23 22:05:04 2023
@author: 86158
"""
def pi_4(n):
s=0
for i in range(n):
sign = (-1) ** i
term=1/(i*2+1)
s += sign * term
return 4 * s
def pi_2_6(n):
s=0
for i in range(1,n+1):
term = 1/(i**2)
s += term
return (6*s)**(1/2)
def LoopString(s):
for i in s:
print(i)
print('-----')
for i in s:
if i == 'a':
break
print(i)
print('------')
for i in s:
if i == 'a':
continue
print(i)
