; Here your code !
(use srfi-1)
(define n (read))
(define (readn n)  (if (= n 0) '() (cons (x->string(read)) (readn (- n 1)) ) ))
(define (reader n)(if(= n 0)'()(cons (readn 5) (reader (- n 1)))))
(define (makeomega n m) (map (lambda (x) (+ x m)) (iota n)) )
(define omega (makeomega 10 0))
(set! omega (map x->string omega))
(define lis (reader n))
(for-each (lambda (x) (begin ()(if (string=? "YES" (last x))(set! omega (lset-intersection string=? omega x))(set! omega (lset-difference string=? omega x)) ))) lis)
(print (car omega))