#include <bits/stdc++.h>
using namespace std;

const int maxn = 300005;

int sa[maxn], sapos[maxn], rmq[2 * maxn];

void suffarray(string str) {
	int n = str.size();
	//cout << str << ' ' << n << endl;
	vector<int> p(n), q(n);
	for (int i = 0; i < n; ++i) {
		p[i] = str[i], sa[i] = i;
	}
	for (int off = 1; off < n; off *= 2) {
		auto cmp = [&] (int a, int b) {
			if (p[a] != p[b]) return p[a] < p[b];
			if (a + off >= n || b + off >= n) return a > b;
			return p[a + off] < p[b + off];
		};
		sort(sa, sa + n, cmp);
		q[sa[0]] = 0;
		for (int i = 1; i < n; ++i) {
			q[sa[i]] = q[sa[i - 1]];
			if (cmp(sa[i - 1], sa[i])) q[sa[i]]++;
		}
		swap(p, q);
	}
	for (int i = 0; i < n; ++i) {
		sapos[sa[i]] = i;
	}
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0);
	int n; cin >> n;
	string str; cin >> str;
	suffarray(str);
	int N = str.size();
	//for (int i = 0; i < N; ++i)
		//cout << sapos[i] << ' ' << str.substr(sa[i]) << endl;
	
	for (int i = 0; i < n; ++i) {
		string s; cin >> s;
		int lor = 0, hir = N;
		for (int i = 0; s[i]; ++i) {
			int lo = lor, hi = hir;
			while (lo < hi) {
				int md = (lo + hi) / 2;
				if (str[sa[md] + i] < s[i]) {
					lo = md + 1;
				} else {
					hi = md;
				}
			} lor = lo, hi = hir;
			while (lo < hi) {
				int md = (lo + hi) / 2;
				if (str[sa[md] + i] <= s[i]) {
					lo = md + 1;
				} else {
					hi = md;
				}
			} hir = lo;
		}
		//cout << lor << ' ' << hir << endl;
		for (int l = lor + N, r = hir + N; l < r; l /= 2, r /= 2) {
			if (l & 1) rmq[l] = max(rmq[l], (int) s.size()), l++;
			if (r & 1) r--, rmq[r] = max(rmq[r], (int) s.size());
		}
	}
	int sol = 0, l = 0, mx = 0;
	for (int i = 0; i < N;) {
		while (l <= i) {
			int len = 0;
			for (int p = sapos[l] + N; p; p /= 2)
				len = max(len, rmq[p]);
			//cout << l << ' ' << len << endl;
			mx = max(mx, l + len);
			l++;
		}
		if (mx <= i) {
			cout << -1; return 0;
		}
		i = mx;
		mx = 0;
		sol++;
	}
	cout << sol;
}