def modpow(b, exp, mod):
    if exp == 0:
        return 1
    if exp == 1:
        return b % MOD
    
    res = modpow(b, exp // 2, mod)
    res *= res
    res %= MOD
    if exp % 2 == 1:
        res *= b
        res %= MOD
    
    return res


N, M = map(int, input().split())
S = input()

g = []
for i in range(N):
    g.append([])

for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    
    g[b].append(a)
    g[a].append(b)

MOD = 998244353

q = 0
for i in range(0, N):
    if S[i] == '?':
        q += 1

ans = 0

for i in range(0, N):
    if S[i] != 'o' and S[i] != '?':
        continue
    n = g[i]
    for j in range(0, len(n)):
        for k in range(0, len(n)):
            if j == k:
                continue
            
            c = 0
            if S[n[j]] == '?':
                c += 1
            elif S[n[j]] != 'a':
                continue
            
            if S[n[k]] == '?':
                c += 1
            elif S[n[k]] != 'i':
                continue
            
            if S[i] == '?':
                c += 1
            
            ans += modpow(26, q - c, MOD)
            ans %= MOD

print(ans)