import math

from decimal import Decimal,  getcontext



getcontext().prec = 100

A, B = input().split()

a = int(A)

b = Decimal(B)

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

import math

from decimal import Decimal,  getcontext



A, B = input().split()

a = int(A)

b = Decimal(B)

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

import math
from decimal import Decimal, getcontext

getcontext().prec = 100
A, B = input().split()
a = int(A)
b = Decimal(B)
print((math.floor(a * b)))

import math
from decimal import Decimal, getcontext

A, B = input().split()
a = int(A)
b = Decimal(B)
print((math.floor(a * b)))

-getcontext().prec = 100