from collections import defaultdict
MOD = 998244353
N,M = list(map(int,input().split()))
S = input()

all_hatena = S.count("?")
edge = defaultdict(list)
for _ in range(M):
    a,b = list(map(int,input().split()))
    a -= 1;b -= 1
    edge[a].append(b)
    edge[b].append(a)

pow_memo = [pow(26,i,MOD) for i in range(all_hatena+1)]
hatena_count = 0
def f(n,depth):
    global hatena_count
    if(depth == 3):return pow_memo[all_hatena - hatena_count]
    ret = 0
    for i in edge[n]:
        if(i in visited):continue
        if("aoi"[depth] != S[i] and S[i] != "?"):continue
        if(S[i] == "?"):hatena_count += 1
        visited.add(i)
        ret += f(i,depth+1)
        ret %= MOD
        visited.remove(i)
        if(S[i] == "?"):hatena_count -= 1
    return ret % MOD

ans = 0
for i in range(N):
    if(S[i] == "a" or S[i] == "?"):
        hatena_count = 0 if S[i] != "?" else 1
        visited = set()
        visited.add(i)
        ans += f(i,1)
        ans %= MOD
print(ans)