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.......,+~7777+7+=?8ZDDD8Z$$7+===~~~~~~~~~~............          ...+888OZZ$Z+$+...            ......?I7=ZZZ8?7?==?=~=*/
#include<bits/stdc++.h>
using namespace std;

typedef long long ll;

string s;
ll n;
ll dp[100005][256];
ll ans;
ll cur;

int main(){

    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin>>n;
    cin>>s;
    for(int i=0;i<n;i++){
        for(int j='a';j<='z';j++){
            dp[i+1][j]=dp[i][j];
        }
        dp[i+1][s[i]]++;
        cur=1;
        for(int j='a';j<='z';j++){
            if(j==s[i])continue;
            cur=cur*(dp[i+1][j]+1)%(long(1e9+7));
        }
        ans=(ans+cur)%(long(1e9+7));
    }
    cout<<ans<<endl;
    
    return 0;
}

Measured memory_bytes: 200528