/* Problem URL: https://codeforces.com/problemset/problem/1950/E */

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template <class T, class comp = less<>>
using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (int i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

const int oo = INT32_MAX >> 1;
const ll OO = INT64_MAX >> 1;


void pre()
{

}

#define TEST 1

void solve()
{
    int n;
    string s;
    cin >> n >> s;

    vi divs;

    auto getdivs = [&]() {
        for (int i = 1; i * i <= n; i++) {
            if (n % i == 0) {
                divs.push_back(i);
                if (i * i != n) {
                    divs.push_back(n / i);
                }
            }
        }
    };

    getdivs();
    sortv(divs);

    string cur;
    V<bool> diff;
    repv(d, divs) {
        fill(all(diff), false);
        while (cur.size() < d) {
            cur.push_back(s[cur.size()]);
            diff.emplace_back();
        }

        int j = 0;
        int c = 0;
        rep(i, n) {
            if (cur[j] != s[i]) {
                diff[j] = true;
                c++;
            }
            j = (j + 1) * (j < d - 1);
        }

        if (c <= 1) {
            cout << d << '\n';
            return;
        }

        if (c == n / d - 1) {
            auto check = [&]() {
                int choice = -1;
                rep(i, d) {
                    if (diff[i]) {
                        if (choice != -1) {
                            return false;
                        }
                        choice = i;
                    }
                }

                char prev = cur[choice];
                cur[choice] = s[choice + d];

                int c = 0;
                int j = 0;
                rep(i, n) {
                    if (cur[j] != s[i]) {
                        c++;
                    }
                    j = (j + 1) * (j < d - 1);
                }

                cur[choice] = prev;

                return c == 1;
            };

            if (check()) {
                cout << d << '\n';
                return;
            }
        }
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    pre();

    int t;
    (TEST && cin >> t) || (t = 1);
    while (t--) {
        solve();
    }
}