# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
N,M = map(int,input().split())
S = list(input())
mod = 998244353

d = {'P':0,'D':1,'C':2,'A':3}

val = [-1]*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[u]>S[v]:
            e[v].append(u)
        else:
            e[u].append(v)

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

def dfs(x):
    
    if val[x] != -1:
        return val[x]
    
    tmp = 0
    
    for ix in e[x]:
        
        tmp += dfs(ix)
        tmp %= mod
    val[x] = tmp
    return tmp
    
ans = 0
for i in range(N):
    if S[i]==0:
        ans += dfs(i)
        ans %= mod
print(ans)