#!/usr/bin/env python3

import math



a, b = input().split()

a = int(a)

b = int(b.replace('.', ''))

print((a*b//100))

#!/usr/bin/env python3



a, b = input().split()

a = int(a)

b = int(float(b)*100+0.5)

print((a*b//100))

#!/usr/bin/env python3
import math

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

#!/usr/bin/env python3
a, b = input().split()
a = int(a)
b = int(float(b) * 100 + 0.5)
print((a * b // 100))

-import math - -b = int(b.replace(".", "")) +b = int(float(b) * 100 + 0.5)