# 1

a = int(input())

b = int(input())

print(round((a * b) / 2, 2))

#2

num = int(input())

print(num - 1, num + 1)

#3

num = int(input())

print(num % 10)

#4

name = input()

money = float(input())

print("Hello,", name, "subscriber! Your current balance is", money, "UAH")

# 1

c = int(input('hyp = '))

h = int(input('h = '))

S = (c*h)/2

print(f'S = {S}')

# 2

n = int(input('n = '))

print(n-1, n+1)

# 3

n = int(input('n = '))

print(n % 10)

# 4

o = input('Your operator: ')

b = float(input("Your balance: "))

c = input("Currency: ")

print(f'Hello, {o} subscriber! Your current balance {b} {c}')