#include <bits/stdc++.h>
#define REP(i, l, r) for (int i = (l); i <= (r); ++ i)
#define DEP(i, r, l) for (int i = (r); i >= (l); -- i)
#define fi first
#define se second
#define pb emplace_back
#define mems(x, v) memset((x), (v), sizeof(x))
using namespace std;
namespace Milkcat {
	typedef long long LL;
	typedef unsigned long long ULL;
	typedef pair<LL, LL> pii;
	const int N = 1e6 + 5, Bs = 99;
	int n, rs, pl[N]; ULL pw[N], hsa[N], hsb[N]; char a[N], b[N];
	void solve(char* A, char* B) {
		pw[0] = 1, hsa[0] = A[0];
		REP(i, 1, n) pw[i] = pw[i - 1] * Bs, pl[i] = 0;
		REP(i, 1, n + 1) hsa[i] = hsa[i - 1] * Bs + A[i];
		DEP(i, n + 1, 0) hsb[i] = hsb[i + 1] * Bs + B[i];
		for (int i = 1, md = 0, r = 0; i <= n; i ++) {
			if (i <= r) pl[i] = min(pl[md * 2 - i], r - i + 1);
			while (A[i - pl[i]] == A[i + pl[i]]) pl[i] ++;
			if (i + pl[i] > r) r = i + pl[i] - 1, md = i;
		}
		REP(i, 1, n) {
			// [i-rs,i-pl[i]][i+pl[i]-2,i+rs-2]
			int p = max(rs, pl[i]);
			for (; p <= i; p ++) {
				ULL x = hsa[i - pl[i]] - hsa[i - p - 1] * pw[p - pl[i] + 1];
				ULL y = hsb[i + pl[i] - 2] - hsb[i + p - 1] * pw[p - pl[i] + 1];
				if (x != y) break;
			}
			rs = max(rs, p);
		}
	}
	int main() {
		cin >> n, a[0] = b[0] = '@';
		REP(i, 1, n) cin >> a[i * 2], a[i * 2 - 1] = '#';
		REP(i, 1, n) cin >> b[i * 2], b[i * 2 - 1] = '#';
		n <<= 1, a[n + 1] = b[n + 1] = '#';
		solve(a, b), reverse(a + 2, a + n + 1), reverse(b + 2, b + n + 1), solve(b, a);
		cout << rs - 1 << '\n';
		return 0;
	}
}
int main() {
	ios::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
	int T = 1;
	while (T --) Milkcat::main();
	return 0;
}