#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <array>
#include <utility>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <queue>
#include <bitset>
#include <tuple>
#include <cmath>
#include <complex>
#include <algorithm>
#include <utility>
#include <regex>
#include <cstdint>
#include <numeric>
#include <functional>
#include <cassert>

using namespace std;
using ll = long long;
using ull = unsigned long long;

constexpr ll INF = 1'000'000'000'000'000'000;
namespace utils{
#define ALL(x) begin(x), end(x)
#define rALL(x) rbegin(x), rend(x)
    template<class T, class Compare> using p_queue = priority_queue<T, vector<T>, Compare>;
    template<class T> using min_queue = p_queue<T, greater<T>>;
    template<class T> using max_queue = p_queue<T, less<T>>;

    template<class T> bool min_update(T& X, const T& A){ if(X > A) {X = A; return true;} return false; }
    template<class T> bool max_update(T& X, const T& A){ if(X < A) {X = A; return true;} return false; }
    using V_Set = unordered_set<int>;
    using E_Set = unordered_map<int, V_Set>;

    ll operator"" _64(unsigned long long x){ return ll(x); }
    ull operator"" _64u(unsigned long long x){ return ull(x); }

    template<class T>
    vector<T> make_mdvector(int n, T t){
        return vector<T>(n, t);
    }
    template<class ...Ts>
    auto make_mdvector(int n, Ts ... ts){
        return vector<decltype(make_mdvector(ts...))>(n, make_mdvector(ts...));
    }

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

    template<class T>
    ostream& operator<<(ostream& os, const vector<T>& v){
        for (auto &&x : v) { os << x << ' '; } cout << endl; return os ;
    }
}
using namespace utils;

class RollingHash {
    vector<vector<ull>> hashed, power;
    string S;
    const vector<ull> bases = {1'234'567, 67'280'421'310'721};
    static constexpr ull MOD = (1ul << 61ul) - 1;

    static inline ull mul(ull a, ull b) {
        constexpr ull mask_30 = (1ull << 30ull) - 1;
        constexpr ull mask_31 = (1ull << 31ull) - 1;
        ull a_u = a >> 31ull;
        ull b_u = b >> 31ull;
        ull a_d = a & mask_31;
        ull b_d = b & mask_31;

        ull mid = a_d * b_u + a_u * b_d;
        ull mid_u = mid >> 30ull;
        ull mid_d = mid & mask_30;

        return calc_mod(a_u * b_u * 2ull + mid_u + (mid_d << 31ull) + a_d * b_d);
    }

    static inline ull calc_mod(ull val) {
        val = (val & MOD) + (val >> 61ull);
        if(val >= MOD) val -= MOD;
        return val;
    }

public:
    explicit RollingHash(string s) : S(std::move(s)) {
        auto N = S.size();
        hashed.resize(2);
        power.resize(2);
        for (int k = 0; k < 2; ++k) {
            auto &&hash = hashed[k];
            auto &&pow = power[k];
            auto &&base = bases[k];
            hash.resize(N + 1);
            hash[0] = 0;
            pow.resize(N + 1);
            pow[0] = 1;
            for (int i = 0; i < N; ++i) {
                hash[i + 1] = calc_mod(mul(hash[i], base) + S[i]);
                pow[i + 1] = calc_mod(mul(pow[i], base));
            } // end i
        }
    }

    // get hash(t) : S[l, r)
    inline ull get(int l, int r, int t) const {
        ull ret = hashed[t][r] + MOD - mul(hashed[t][l], power[t][r-l]);
        ret = calc_mod(ret);
        return ret;
    }

    inline pair<ull, ull> get(int l, int r) const {
        return {get(l, r, 0), get(l, r, 1)};
    }
};

class solver{
    istream& is;
    ostream& os;

public:
    solver(istream& I, ostream& O) :is(I), os(O) {}
    ll N, M;
    void run();
};

int main(int argc, char *argv[]) {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << setprecision(16) << scientific;
#ifdef DEBUG
    string test_cases = "test_roling_hash.txt";
    cerr << test_cases << " -->" << endl;
    auto fs = fstream(test_cases, fstream::in);
    int loop = 0;
    while(fs) {
        loop++;
        cout << '#' << loop << "#------\n";
        solver(fs, cout).run();
    }
    if(loop <= 1) {
        cout << "===" << endl;
        while(cin) solver(cin, cout).run();
    }
#else
    solver(cin, cout).run();
#endif
    return 0;
}

void solver::run(){
    string S;
    is >> N >> S;
    if(!is) return;
    string rS = S; reverse(ALL(rS));
    RollingHash RH(S), rRH(rS);

    for (int length = 2; length <= N; ++length) {
        ll cur = length;
        bool rev = true;
        bool check = true;
        while(cur < N){
            ll r = min(N, cur + length-1);
            ll len = r - cur;
            if(rev){
                if(RH.get(cur, r) != rRH.get(N - length + 1, N - length + 1 + len)){
                    check = false; break;
                }
            }
            else{
                if(RH.get(cur, r) != RH.get(1, 1+len)){
                    check = false; break;
                }
            }
            rev = !rev;
            cur = r;
        }
        if(check){
            os << length << endl;
            return;
        }
    } // end i

}



Measured memory_bytes: 69380