import sequtils,strutils,algorithm,math,sugar,macros,strformat
template times*(n:int,body) = (for _ in 0..<n: body)
template `max=`*(x,y) = x = max(x,y)
proc getchar_unlocked():char {. importc:"getchar_unlocked",header: "<stdio.h>" .}
proc scan(): int =
  var minus = false
  while true:
    var k = getchar_unlocked()
    if k == '-' : minus = true
    elif k < '0' or k > '9': break
    else: result = 10 * result + k.ord - '0'.ord
  if minus: result *= -1
let n = scan()
let m = scan()
let S = toSeq(stdin.readLine().items).mapIt:
  case it:
  of 'P':0
  of 'D':1
  of 'C':2
  else : 3
var DC = newSeq[(int,int)]()
var CA = newSeq[int]()
var ans = newSeq[int](n)
m.times:
  var u = scan() - 1
  var v = scan() - 1
  if S[u] > S[v]: (u,v) = (v,u)
  if S[v] - S[u] != 1 : continue
  case S[v]:
  of 1 : ans[v] += 1
  of 2 : DC &= (u,v)
  else : CA &= u
for dc in DC: ans[dc[1]] += ans[dc[0]]
echo CA.mapIt(ans[it]).sum() mod 1000000007