#include "bits/stdc++.h"
using namespace std;
#define int long long
//#define endl '\n'
int mod=1e9+7;
int mod2=998244353;
const int INF=1e9;

signed main(){
  int n;
  string s;
  cin>>n>>s;
  int ans=1;
  map<char,int> mp;
  for(int i=0;i<n;i++)mp[s[i]]++;
  for(char c='a';c<='z';c++){
    if(mp[c]>0)ans*=(mp[c]+1);
    ans%=mod;
  }
  ans+=mod;
  cout<<(ans-1LL)%mod<<endl;
}

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