import sys
sys.setrecursionlimit(10**8)
n,m=map(int,input().split())
s=list(input())
connect=[[] for _ in range(n)]
hate=s.count("?")
for _ in range(m):
    a,b=map(int,input().split())
    a-=1
    b-=1
    connect[a].append(b)
    connect[b].append(a)
ans=0
mod=998244353
def DFS(now,deepth,used):
    global ans
    global visited
    if deepth==2:
        cnt=1
        for _ in range(hate-used):
            cnt*=26
            cnt%=mod
        ans+=cnt
        ans%=mod
        return 0
    for to in connect[now]:
        if s[to] == word[deepth+1] or s[to]=="?":
            if not visited[to]:
                visited[to]=True
                if s[to]=="?":
                    DFS(to,deepth+1,used+1)
                else:
                    DFS(to,deepth+1,used)
                visited[to]=False
word="aoi"
for start in range(n):
    visited=[False]*n
    if s[start] in "?a":
        visited[start]=True
        if s[start]=="?":
            DFS(start,0,1)
        else:
            DFS(start,0,0)
ans%=mod
print(ans)