#include <bits/stdc++.h>
#define _for(i, a, b) for (int i = a; i <= b; ++i)
#define for_(i, a, b) for (int i = a; i >= b; --i)
#define far(i, vec) for (auto i : vec)
#define bdmd int mid = (l + r) >> 1
typedef long double ldb;
typedef long long ll;
typedef double db;
typedef std::pair <int, int> pii;
typedef std::pair <ll, ll> pll;
namespace IO {
	int rnt () {
		int x = 0, w = 1; char c = getchar ();
		while (!isdigit (c)) { if (c == '-') w = -1; c = getchar (); }
		while (isdigit (c)) x = (x << 3) + (x << 1) + (c ^ 48), c = getchar ();
		return x * w;
	}
}
const int N = 2e5 + 10, B = 131, P = 1e9 + 7;
namespace SOLVE {
	using namespace IO;
	int n, b[N], ha[2][N][2], ans;
	char _[2][N], s[N], t[N];
	void Init () {
		b[0] = 1;
		_for (i, 1, n)
			b[i] = 1ll * b[i - 1] * B % P;
		_for (i, 1, n) {
			ha[0][i][0] = (1ll * ha[0][i - 1][0] * B + s[i]) % P;
			ha[1][i][0] = (1ll * ha[1][i - 1][0] * B + t[i]) % P;
		}
		for_ (i, n, 1) {
			ha[0][i][1] = (1ll * ha[0][i + 1][1] * B + s[i]) % P;
			ha[1][i][1] = (1ll * ha[1][i + 1][1] * B + t[i]) % P;
		}
		return;
	}
	int Q (int o, int d, int l, int r) {
		// printf ("%d %d %d %d\n", o, d, l, r);
		// printf ("%d %d %d\n", ha[o][r + 1][d], ha[o][l][d], b[r - l + 1]);
		// printf ("%d %d %d\n", ha[o][r][d], ha[o][l - 1][d], b[r - l + 1]);
		return d ? (ha[o][l][d] - 1ll * ha[o][r + 1][d] * b[r - l + 1] % P + P) % P
				 : (ha[o][r][d] - 1ll * ha[o][l - 1][d] * b[r - l + 1] % P + P) % P;
	}
	void In () {
		n = rnt ();
		scanf ("%s", _[0] + 1);
		scanf ("%s", _[1] + 1);
		return;
	}
	void Solve () {
		ans = 1;
		s[1] = s[n * 2 + 2] = s[n * 2 + 3] = '#';
		t[1] = t[2] = t[n * 2 + 3] = '#';
		_for (i, 1, n) {
			s[i * 2] = _[0][i], s[i * 2 + 1] = '#';
			t[i * 2 + 2] = _[1][i], t[i * 2 + 1] = '#';
		}
		n = n * 2 + 3;
		Init ();
		// puts (s + 1);
		// puts (t + 1);
		// printf ("%d %d\n", Q (1, 0, 1, 2), Q (1, 1, n - 2, n - 1));
		// printf ("%d %d\n", Q (0, 0, 3, 3), Q (1, 1, n - 2, n - 2));
		// printf ("%d %d %d\n", ha[0][1][0], ha[0][2][0], b[1]);
		// printf ("%d %d %d\n", ha[1][n - 2][0], ha[1][n - 1][0], b[1]);
		_for (i, 1, n) {
			int l = 0, r = std::min (i - 1, n - i);
			while (l <= r) {
				bdmd;
				if (Q (0, 0, i - mid, i)
				 == Q (0, 1, i, i + mid))
					l = mid + 1;
				else
					r = mid - 1;
			}
			int len = r;
			l = 1, r = std::min (i - 1 - len, n - i - len);
			while (l <= r) {
				bdmd;
				if (Q (0, 0, i - len - mid, i - len - 1)
				 == Q (1, 1, i + len + 1, i + len + mid))
					l = mid + 1;
				else
					r = mid - 1;
			}
			// printf ("%d %d %d %c\n", i, len, r, s[i]);
			len += r;
			ans = std::max (len, ans);
		}
		_for (i, 1, n) {
			int l = 0, r = std::min (i - 1, n - i);
			while (l <= r) {
				bdmd;
				if (Q (1, 0, i - mid, i)
				 == Q (1, 1, i, i + mid))
					l = mid + 1;
				else
					r = mid - 1;
			}
			int len = r;
			l = 1, r = std::min (i - 1 - len, n - i - len);
			while (l <= r) {
				bdmd;
				if (Q (0, 0, i - len - mid, i - len - 1)
				 == Q (1, 1, i + len + 1, i + len + mid))
					l = mid + 1;
				else
					r = mid - 1;
			}
			len += r;
			ans = std::max (len, ans);
		}
		return;
	}
	void Out () {
		printf ("%d\n", ans);
		return;
	}
}
int main () {
#ifndef ONLINE_JUDGE
	freopen ("data.in", "r", stdin);
	// freopen ("data.out", "w", stdout);
#endif
	SOLVE::In ();
	SOLVE::Solve ();
	SOLVE::Out ();
	return 0;
} /*
#p#k#u#s#c###
###p#k#u#k#p#
*/