import java.io.*;
import java.util.*;

class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader bu=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb=new StringBuilder();
        int n=Integer.parseInt(bu.readLine());
        char s[]=bu.readLine().toCharArray();
        HashMap<Character,Integer> mp=new HashMap<>();
        String x="yukicoder";
        int i,l=x.length();
        for(i=0;i<l;i++) mp.put(x.charAt(i),i+1);
        mp.put('?',0);

        long dp[][]=new long[2][l+1],M=(int)1e9+7;
        dp[0][0]=1; //use this only for non ? marks
        for(i=0;i<n;i++)
        if(mp.get(s[i])!=null)
        {
            int in=mp.get(s[i]);
            if(in>0)    //all subsequences which either have a ? or dont
            {
                dp[0][in]=(dp[0][in]+dp[0][in-1])%M;
                dp[1][in]=(dp[1][in]+dp[1][in-1])%M;
            }
            else    //we can use at most 1 ?
            for(int j=l;j>0;j--) dp[1][j]=(dp[0][j-1]+dp[1][j])%M;
        }
        System.out.println((dp[0][l]+dp[1][l])%M);
    }
}