# -*- coding: utf-8 -*-

a, b = input().split()

print((int(a)*int(b.replace('.', ''))//100))
# -*- coding: utf-8 -*-

a, b = input().split()

b_arr = b.split('.')

print((int(a)*int(b_arr[0])+int(a)*int(b_arr[1])//100))
# -*- coding: utf-8 -*-
a, b = input().split()
print((int(a) * int(b.replace(".", "")) // 100))

# -*- coding: utf-8 -*-
a, b = input().split()
b_arr = b.split(".")
print((int(a) * int(b_arr[0]) + int(a) * int(b_arr[1]) // 100))

-print((int(a) * int(b.replace(".", "")) // 100)) +b_arr = b.split(".") +print((int(a) * int(b_arr[0]) + int(a) * int(b_arr[1]) // 100))