(define (main args)
  (let* ([n (read)]
         [m (read)]
         [chv (string->vector (symbol->string (read)))]
         [adv (make-vector n '())]
         [ctv (make-vector n 0)]
         [md (+ 7 (expt 10 9))])
    (let loop ([x m])
      (cond [(zero? x) #t]
            [else
             (let* ([p1 (- (read) 1)]
                    [p2 (- (read) 1)])
               (vector-set! adv p1 (cons p2 (vector-ref adv p1)))
               (vector-set! adv p2 (cons p1 (vector-ref adv p2))))
             (loop (- x 1))]))
    (for-each (^i (vector-set! ctv i
                               (length
                                (filter (^j (eq? #\A (vector-ref chv j)))
                                        (vector-ref adv i)))))
              (filter (^i (eq? #\C (vector-ref chv i))) (iota n)))
    (for-each (^i (vector-set! ctv i
                               (remainder (apply + (map (^j (vector-ref ctv j))
                                             (filter (^j (eq? #\C (vector-ref chv j)))
                                                     (vector-ref adv i)))) md)))
              (filter (^i (eq? #\D (vector-ref chv i))) (iota n)))
    (for-each (^i (vector-set! ctv i
                               (remainder (apply + (map (^j (vector-ref ctv j))
                                             (filter (^j (eq? #\D (vector-ref chv j)))
                                                     (vector-ref adv i)))) md)))
              (filter (^i (eq? #\P (vector-ref chv i))) (iota n)))
    (print
     (remainder (apply +
                       (map (^j (vector-ref ctv j))
                            (filter (^i (eq? #\P (vector-ref chv i))) (iota n)))) md)))
  0)