implicit none
integer(8) a,b,i
integer(8),allocatable :: x(:,:)
read(*,*) a
read(*,*) b
allocate (x(1:b,1:2))
do i=1,b
    read(*,*) x(i,1),x(i,2)
    if (x(i,1)==a) then
        a=x(i,2)
    else if (x(i,2)==a) then
        a=x(i,1)
    end if
end do
write(*,*) a
end