program main
    implicit none
    integer(4):: n, li, ri
    character(6):: s, s1
    
    li=1
    ri=n/2+1

    print*, 1
    read*, s1
    if (s1 == 'Vacant') stop

    do while(ri-li > 1)
        print'(i0)', 2*((ri+li)/2)-1
        read*, s
        if (trim(s) == 'Vacant') stop
        if (trim(s) == trim(s1)) then
            li = (ri+li)/2
        else
            ri = (ri+li)/2
        end if
    end do

    print*, (ri+li)-1
end program main