import sys
input = sys.stdin.readline

mod=998244353

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

E=[[] for i in range(N)]

for i in range(M):
    x,y=map(int,input().split())
    x-=1
    y-=1
    E[x].append(y)
    E[y].append(x)

ko=S.count("?")

LIST=[]

for i in range(N):
    for to in E[i]:
        for toto in E[to]:
            if i==toto:
                continue
            LIST.append((i,to,toto))

POW26=[1]
for i in range(10000):
    POW26.append(POW26[-1]*26%mod)
    
ANS=0
for x,y,z in LIST:
    count=0
    if S[x]=="a":
        pass
    elif S[x]=="?":
        count+=1
    else:
        continue

    if S[y]=="o":
        pass
    elif S[y]=="?":
        count+=1
    else:
        continue

    if S[z]=="i":
        pass
    elif S[z]=="?":
        count+=1
    else:
        continue

    ANS=(ANS+POW26[ko-count])%mod

print(ANS)