#from collections import deque,defaultdict

from sys import stdin

input = stdin.readline

printn = lambda x: print(x,end='')

inn = lambda : int(input())

inl   = lambda: list(map(int, input().split()))

inm   = lambda:      map(int, input().split())

ins = lambda : input().strip()

DBG = True # and False

BIG = 10**18

R = 10**9 + 7



def ddprint(x):

  if DBG:

    print(x)



from decimal import Decimal

a,b = input().split()

a = int(a)

b = Decimal(b)

b = int(100*b)

print(a*b//100)

#from collections import deque,defaultdict

from sys import stdin

input = stdin.readline

printn = lambda x: print(x,end='')

inn = lambda : int(input())

inl   = lambda: list(map(int, input().split()))

inm   = lambda:      map(int, input().split())

ins = lambda : input().strip()

DBG = True # and False

BIG = 10**18

R = 10**9 + 7



def ddprint(x):

  if DBG:

    print(x)



from decimal import Decimal

a,b = input().split()

a = int(a)

b = float(b)

b = round(100*b)

print(a*b//100)

# from collections import deque,defaultdict
from sys import stdin

input = stdin.readline
printn = lambda x: print(x, end="")
inn = lambda: int(input())
inl = lambda: list(map(int, input().split()))
inm = lambda: map(int, input().split())
ins = lambda: input().strip()
DBG = True  # and False
BIG = 10**18
R = 10**9 + 7


def ddprint(x):
    if DBG:
        print(x)


from decimal import Decimal

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

# from collections import deque,defaultdict
from sys import stdin

input = stdin.readline
printn = lambda x: print(x, end="")
inn = lambda: int(input())
inl = lambda: list(map(int, input().split()))
inm = lambda: map(int, input().split())
ins = lambda: input().strip()
DBG = True  # and False
BIG = 10**18
R = 10**9 + 7


def ddprint(x):
    if DBG:
        print(x)


from decimal import Decimal

a, b = input().split()
a = int(a)
b = float(b)
b = round(100 * b)
print(a * b // 100)

-b = Decimal(b) -b = int(100 * b) +b = float(b) +b = round(100 * b)