20210818

'''
data = input()
data = int(data)
s = 0

for i in range(1, data+1):
    if i % 10 == 1:
        s += 1

print(s)
'''
'''
value = int(input())

for i in range(10000):
    print(value%10)
    value = value // 10
    if value == 0:
        break
'''
'''
n = input()
n = int(n)
s = 0

for i in range(10000):
    s += (n%10)
    n = n // 10
    if n == 0:
        print(s)
        break

n = s
s = 0

for i in range(10000):
    s += (n%10)
    n = n // 10
    if n == 0:
        print(s)
        break

n = s
s = 0

for i in range(10000):
    s += (n%10)
    n = n // 10
    if n == 0:
        print(s)
        break
'''
'''
def sum(n):
    s = 0
    for i in range(10000):
        s += (n % 10)
        n = n // 10
        if n == 0:
            return s

n = input()
n = int(n)

for i in range(10000):
    n = sum(n)
    if n < 10:
        print(n)
        break
'''
'''
a, b = input().split()
a = int(a)
b = int(b)
s = 0

print(a+b)
print(a-b)
print(a*b)
print(a//b)
print(a%b)
print(round(a/b, 2))
'''