"use strict";
function Main(input) {
    let cin = new Inputer(input);
    let N = cin.getInt(), S = cin.getStr();
    let C = {};
    for (let n = 0; n < S.length; n++) {
        let c = C[S[n]] || 0;
        C[S[n]] = ++c;
    }
    const MOD = 1e9 + 7;
    let ans = 1;
    for (let n in C) {
        ans = (ans * (C[n] + 1)) % MOD;
    }
    ans = (ans - 1 + MOD) % MOD;
    console.log(ans);
}
class Inputer{constructor(t){if(typeof t=='undefined')throw new Error('引数（stdin）を省略できません！');this.cnt=0,this.items=t.split(/\n|\s/)}getInt(){return this.items[this.cnt++]-0}getIntArray(t){if(typeof t=='undefined')throw new Error('引数（1以上）を省略できません！');let r=new Array(t);for(let e=0;e<t;e++)r[e]=this.getInt();return r}getStr(){return this.items[this.cnt++]}getStrArray(t){if(typeof t=='undefined')throw new Error('引数（1以上）を省略できません！');let r=new Array(t);for(let e=0;e<t;e++)r[e]=this.getStr();return r}}
if (typeof window == "undefined") Main(require("fs").readFileSync("/dev/stdin", "utf8"));