#include <bits/stdc++.h>
using namespace std;

int main(){
    int N;
    string S;
    cin >> N >> S;
    vector<int> C(10, 0);
    for (char c : S) C[c-'0']++;

    int ans = 0;
    for (int n = 0; n < 1000; n++){
        auto c = C;
        bool ok = true;
        c[n%10]--, c[(n/10)%10]--, c[n/100]--;
        for (int x : c) if (x < 0) ok = false;
        if (ok) ans++;
    }

    cout << ans << endl;
}