def main():

    from decimal import Decimal

    A, B = list(map(Decimal, input().split()))

    print((int(A * B)))





if __name__ == '__main__':

    main()



# import sys

# input = sys.stdin.readline

# 

# sys.setrecursionlimit(10 ** 7)

# 

# (int(x)-1 for x in input().split())

# rstrip()

#

# def binary_search(*, ok, ng, func):

#     while abs(ok - ng) > 1:

#         mid = (ok + ng) // 2

#         if func(mid):

#             ok = mid

#         else:

#             ng = mid

#     return ok

def main():

    A, B = input().split()



    A = int(A)

    B_int, B_frac = list(map(int, B.split('.')))  # 整数部分, 小数部分

    L = len(str(B_frac))  # 小数部分の桁数



    ans = (A * (B_int * 100 + B_frac)) // 100



    print(ans)





if __name__ == '__main__':

    main()

def main():
    from decimal import Decimal

    A, B = list(map(Decimal, input().split()))
    print((int(A * B)))


if __name__ == "__main__":
    main()
# import sys
# input = sys.stdin.readline
#
# sys.setrecursionlimit(10 ** 7)
#
# (int(x)-1 for x in input().split())
# rstrip()
#
# def binary_search(*, ok, ng, func):
#     while abs(ok - ng) > 1:
#         mid = (ok + ng) // 2
#         if func(mid):
#             ok = mid
#         else:
#             ng = mid
#     return ok

def main():
    A, B = input().split()
    A = int(A)
    B_int, B_frac = list(map(int, B.split(".")))  # 整数部分, 小数部分
    L = len(str(B_frac))  # 小数部分の桁数
    ans = (A * (B_int * 100 + B_frac)) // 100
    print(ans)


if __name__ == "__main__":
    main()

-    from decimal import Decimal - -    A, B = list(map(Decimal, input().split())) -    print((int(A * B))) +    A, B = input().split() +    A = int(A) +    B_int, B_frac = list(map(int, B.split(".")))  # 整数部分, 小数部分 +    L = len(str(B_frac))  # 小数部分の桁数 +    ans = (A * (B_int * 100 + B_frac)) // 100 +    print(ans) -# import sys -# input = sys.stdin.readline -# -# sys.setrecursionlimit(10 ** 7) -# -# (int(x)-1 for x in input().split()) -# rstrip() -# -# def binary_search(*, ok, ng, func): -#     while abs(ok - ng) > 1: -#         mid = (ok + ng) // 2 -#         if func(mid): -#             ok = mid -#         else: -#             ng = mid -#     return ok