# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
N,M = map(int,input().split())
S = list(input())
mod = 998244353
import sys
# sys.setrecursionlimit(10**6)
d = {'P':0,'D':1,'C':2,'A':3}

val = [0]*N
S = [d[i] for i in S]
e = [[] for _ in range(N)]
for i in range(M):
    u,v = map(int,input().split())
    u -= 1
    v -= 1
    if abs(S[u]-S[v])==1:
        if S[v]>S[u]:
            e[v].append(u)
        else:
            e[u].append(v)

for i in range(N):
    if S[i]==3:
        val[i]=1

for i in range(3,0,-1):
    
    for j in range(N):
        
        if S[j]==i:
            
            for ix in e[j]:
                
                val[ix] = (val[ix]+val[j])%mod
print(sum(val[i] for i in range(N) if S[i]==0)%mod)
# print(val)