# coding: utf-8
# Your code here!
class Node:
	def __init__(self):
		self.edge=[]
		self.degree=0
		self.word=""
		self.cnt=0
	
	def add_edge(self,new_edge):
		self.edge.append(new_edge)
		self.degree+=1


class Edge:
	def __init__(self,node_a,node_b):
		node_a.add_edge(self)
		node_b.add_edge(self)
		self.node=(node_a,node_b)


class Graph:
	def __init__(self):
		self.node={}
		self.edge=[]
	
	def add_edge(self,new_edge):
		if not new_edge[0] in self.node:
			self.node[new_edge[0]]=Node()
		if not new_edge[1] in self.node:
			self.node[new_edge[1]]=Node()
		self.edge.append(Edge(self.node[new_edge[0]],self.node[new_edge[1]]))

n,m=map(int,input().split())
s=input()
g=Graph()
for i in range(m):
    g.add_edge(list(map(int,input().split())))
for i in range(len(s)):
    if i+1 in g.node:
        g.node[i+1].word=s[i]

for i in g.edge:
    a,b=i.node[0],i.node[1]
    if (a.word=="P") and (b.word=="D"):
        b.cnt+=1
    if (a.word=="D") and (b.word=="P"):
        a.cnt+=1
        
for i in g.edge:
    a,b=i.node[0],i.node[1]
    if (a.word=="D") and (b.word=="C"):
        b.cnt+=a.cnt
    if (a.word=="C") and (b.word=="D"):
        a.cnt+=b.cnt
c=0

for i in g.edge:
    a,b=i.node[0],i.node[1]
    if (a.word=="C") and (b.word=="A"):
        c+=a.cnt
    if (a.word=="A") and (b.word=="C"):
        c+=b.cnt
print(c)