#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>
using namespace std;

#define sim template < class c
#define ris return * this
#define mor > muu & operator << (
#define R22(r) sim > typename \
  enable_if<1 r sizeof dud<c>(0), muu&>::type operator<<( c g) {
sim > struct rge { c b, e; };
sim > rge<c> range(c h, c n) { return {h, n}; }
sim > auto dud(c * r) -> decltype(cerr << *r);
sim > char dud(...);
struct muu {
	#ifdef LOCAL
	stringstream a;
	~muu() { cerr << a.str() << endl; }
	R22(<) a << boolalpha << g; ris; }
	R22(==) ris << range(begin(g), end(g)); }
	sim, class b mor pair < b, c> r) { ris << "(" << r.first << ", " << r.second << ")"; }
	sim mor rge<c> u) {
		a << "[";
		for (c i = u.b; i != u.e; ++i) 
			*this << ", " + 2 * (i == u.b) << *i;
		ris << "]";
	}
#else
sim mor const c&) { ris; }
#endif
muu & operator()() { ris; }
};
#define imie(r...) "[" #r ": " << (r) << "] "
#define debug (muu() << __FUNCTION__ << "#" << __LINE__ << ": ")

void manacher(string s, int n, vector<int>& r) {
	r.resize(s.size() * 2);
	for (int i = 0, m = 0, k = 0, p = 0; i < 2 * n - 1; m = i ++ - 1) {
		while (p < k && i / 2 + r[m] != k)
			r[i++] = min(r[m--], (k+1 - p++) / 2);
		while (k+1 < n && p > 0 && s[k+1] == s[p-1]) k++, p--;
		r[i] = (k+ 1 - p++) / 2;
	}
}

void solve() {
	int n;
	cin >> n;
	string s;
	cin >> s;
	vector<int> r;
	manacher(s, n, r);
	int res = n;
	debug << r;
	for (int i = 0; i < n; i ++) {
		if (i + r[2 * i] == n - 1) res = min(res, n - 2 * r[2 * i] -1);
		if (i + r[2 * i + 1] == n - 1) if (i < n - 1) res = min(res, n - 2 * r[2 * i + 1]);
	}
	cout << res << "\n";
}

int main() {
	ios_base::sync_with_stdio(0);
	solve();
}