program ABC169C
    implicit none
    integer(8)::i
    integer(16)::A,B
    character(10)::S
    read*,A,S
    do i=1,len_trim(S)
        if(S(i:i)==".")then
            S=S(1:i-1)//S(i+1:len_trim(S))
            exit
        end if
    end do
    read(S,*)B
    print'(i0)',(A*B)/100
end program ABC169C