# coding: utf-8

import sys

import decimal



sr = lambda: sys.stdin.readline().rstrip()

ir = lambda: int(sr())

lr = lambda: list(map(int, sr().split()))



A, B = sr().split()

A = int(A)

B = decimal.Decimal(B) * 100

answer = A*B // 100

print(answer)

# coding: utf-8

import sys



sr = lambda: sys.stdin.readline().rstrip()

ir = lambda: int(sr())

lr = lambda: list(map(int, sr().split()))



A, B = sr().split()

A = int(A)

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

answer = A*B // 100

print(answer)

# coding: utf-8
import sys
import decimal

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))
A, B = sr().split()
A = int(A)
B = decimal.Decimal(B) * 100
answer = A * B // 100
print(answer)

# coding: utf-8
import sys

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))
A, B = sr().split()
A = int(A)
B = int(float(B) * 100 + 0.5)
answer = A * B // 100
print(answer)

-import decimal -B = decimal.Decimal(B) * 100 +B = int(float(B) * 100 + 0.5)