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)