#include <bits/stdc++.h>
using namespace std;
#include<atcoder/modint>
using mint=atcoder::modint998244353;
int n,m;
string s;
int hate=0;
mint ans=0;
string word="aoi";
void DFS(int now,int deepth,int used,vector<bool>&visited,vector<vector<int>>&connect){
    if (deepth==2){
        mint cnt=1;
        for(int i=0;i<hate-used;i++){
            cnt*=26;
        }
        ans+=cnt;
    }
    for(auto to:connect[now]){
        if(s[to]==word[deepth+1] || s[to]=='?'){
            if(!visited[to]){
                visited[to]=true;
                if(s[to]=='?')DFS(to,deepth+1,used+1,visited,connect);
                else DFS(to,deepth+1,used,visited,connect);
                visited[to]=false;
            }
        }
    }
    
}
int main(){
    cin>>n>>m;
    cin>>s;
    vector<vector<int>>connect(n);
    for(int i=0;i<n;i++)if(s[i]=='?')hate++;
    for(int i=0;i<m;i++){
        int a,b;cin>>a>>b;
        a--;b--;
        connect[a].push_back(b);
        connect[b].push_back(a);
    }
    for(int start=0;start<n;start++){
        vector<bool>visited(n,false);
        if (s[start]=='a'||s[start]=='?'){
            visited[start]=true;
            if (s[start]=='?')DFS(start,0,1,visited,connect);
            else DFS(start,0,0,visited,connect);
        }
    }
    cout<<ans.val()<<endl;
}