TYPES = "PDCA"

N,M = gets.split.map(&:to_i)
S = gets.chomp
V = Array.new(N + 1, -1)
G = Array.new(N + 1){[]}
dp = Array.new(4){ Array.new(N + 1, 0) }

(1 .. N).each do |v|
  t = TYPES.index(S[v - 1])
  V[v] = t
end

M.times do 
  a,b = gets.split.map(&:to_i)
  G[a] << b
  G[b] << a
end

(1 .. N).each do |v|
  dp[0][v] = 1 if V[v] == 0
end

(1 .. 3).each do |t|
  (1 .. N).each do |v|
    next unless V[v] == t
    
    dp[t][v] = G[v].inject(0) do |s, u|
      V[u] == t - 1 ? s + dp[t - 1][u] : s
    end
  end
end
puts dp[3].sum