program main
	implicit none
	integer n,i,j
	integer:: kaz(0:9)=1,d(4)
	character:: hantei*3
	read(*,*)n
	do i=1,n
		read(*,*)d(1:4),hantei
		if(trim(hantei)=="YES")then
			do j=1,4
				kaz(d(j))=kaz(d(j))*2
			enddo
		else
			do j=1,4
				kaz(d(j))=0
			enddo			
		endif		
	enddo
	write(*,*)maxloc(kaz)-1
end program main