#include <iostream>

using namespace std;

const long long OO = 1e9 + 7;
const int MAXN = 1e5 + 5;

long long base[3], p[3][MAXN], h[3][MAXN], rev_h[3][MAXN];
int n;
string s;

long long getH(int ty, int i, int j) {
    long long tmp = (h[ty][j] - h[ty][i - 1] * p[ty][j - i + 1]);
    return tmp;
}

long long getRevH(int ty, int i, int j) {
    long long tmp = (rev_h[ty][i] - rev_h[ty][j + 1] * p[ty][j - i + 1]);
    return tmp;
}

bool check(int s1, int e1, int s2, int e2) {
    if (s1 <= 0 || e1 <= 0) return false;
    for(int ty = 1; ty <= 2; ++ty) {
        long long tmp1 = getH(ty, s2, e2);
        long long tmp2 = getRevH(ty, s1, e1);
        if (tmp1 != tmp2) return false;
    }
    return true;
}

void initH(const string &s) {
    int n = s.size();
    base[1] = 233; base[2] = 719;
    //MOD[1] = OO; MOD[2] = OO + 6;
    p[1][0] = p[2][0] = 1;
    for(int ty = 1; ty <= 2; ++ty) {
        for(int i = 1; i <= n; ++i) p[ty][i] = (p[ty][i - 1] * base[ty]);
        for(int i = 1; i <= n; ++i) h[ty][i] = (h[ty][i - 1] * base[ty] + s[i - 1] - 'a' + 1);
        for(int i = n; i > 0; --i) rev_h[ty][i] = (rev_h[ty][i + 1] * base[ty] + s[i - 1] - 'a' + 1);
    }
}

int main()
{
//    cout << "Hello world!" << endl;
    ios_base::sync_with_stdio(false); cin.tie(0);
    cin >> n;
    cin >> s;
    initH(s);
    int res = 0;
    for(int i = n; i > 0; --i) {
        int e2 = n;
        int s2 = i;
        int l = (n - i + 1);
        if (check(s2 - l + 1, s2, s2, e2)) {
            res = max(res, 2 * l - 1);
        }
        if (check(s2 - 1 - l + 1, s2 - 1, s2, e2)) {
            res = max(res, 2 * l);
        }
    }
    cout << n - res << '\n';
    return 0;
}