#a, b = map(float, input().split())



a, b = input().split()

from decimal import Decimal

import math

print((math.floor(int(a)*Decimal(b))))

#解放1

a, b = input().split()

b = b.replace(".", "")

print((int(a)*int(b)//100))
# a, b = map(float, input().split())
a, b = input().split()
from decimal import Decimal
import math

print((math.floor(int(a) * Decimal(b))))

# 解放1
a, b = input().split()
b = b.replace(".", "")
print((int(a) * int(b) // 100))

-# a, b = map(float, input().split()) +# 解放1 -from decimal import Decimal -import math - -print((math.floor(int(a) * Decimal(b)))) +b = b.replace(".", "") +print((int(a) * int(b) // 100))