import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
N = ni()
S = list(input())
s = "yukicoder"
s = list(s)
p = [s]
for i in range(9):
    z = s.copy()
    z[i] = "?"
    p.append(z)
    

ans= 0
mod = 10**9+7
for _ in range(10):
    z = p[_]
    dp = [[0 for i in range(len(z)+1)] for i in range(N+1)]
    dp[0][0]=1

    for i in range(N):
        for j in range(len(z)+1):
            dp[i+1][j]+=dp[i][j]
            dp[i+1][j]%=mod
        for j in range(len(z)):
            if S[i]==z[j]:
                dp[i+1][j+1]+=dp[i][j]
                dp[i+1][j+1]%=mod
    ans += dp[-1][-1]
    ans %= mod
    #print(z)
    #print(dp,"\n")
print(ans)