// compile: g++ -o data data.cpp -std=gnu++20 -DLOCAL
// run: ./data < data.in
#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#endif
#define sz(v) ((int)(v).size())
#define PV(v) for (int i=0;i<v.size();++i)cout<<v[i]<<" ";cout<<endl;
#define INTINF 9223372036854775807
#define int long long

using namespace std;

int32_t main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int _; cin >> _;
    while (_--) {
        int n; cin >> n;
        string s;
        char minv = 127;
        cin >> s;
        for (int i = 0; i < n; ++i) minv = min(minv, s[i]);
        int p;
        for (p = n-1; p >= 0; --p) {
            if (s[p] == minv) break;
        }
        cout << s[p];
        for (int i = 0; i < n; ++i) {
            if (i == p) continue;
            cout << s[i];
        }
        cout << endl;
    }

    return 0;
}