/* @Date : 2025-08-18 13:18:37
@Author : hasan_86 */
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define endl "\n"
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
vector<int> sort_cyclic_shift(string &s) {
int n = s.size();
vector<int> p(n), c(n), cnt(max(n, 256));
for (int i = 0; i < n; i++) {
cnt[s[i]]++;
}
for (int i = 1; i < 256; i++) {
cnt[i] += cnt[i - 1];
}
for (int i = n - 1; i >= 0; i--) {
p[--cnt[s[i]]] = i;
}
int cl = 1;
c[p[0]] = 0;
for (int i = 1; i < n; i++) {
if (s[p[i]] != s[p[i - 1]])
cl++;
c[p[i]] = cl - 1;
}
for (int l = 0; (1 << l) < n; l++) {
vector<int> pn(n), cn(n);
for (int i = 0; i < n; i++) {
pn[i] = p[i] - (1 << l);
if (pn[i] < 0)
pn[i] += n;
}
fill(begin(cnt), begin(cnt) + cl, 0);
for (int i = 0; i < n; i++) {
cnt[c[pn[i]]]++;
}
for (int i = 1; i < cl; i++) {
cnt[i] += cnt[i - 1];
}
for (int i = n - 1; i >= 0; i--) {
p[--cnt[c[pn[i]]]] = pn[i];
}
cl = 1;
cn[p[0]] = 0;
for (int i = 1; i < n; i++) {
pii prv = {c[p[i - 1]], c[(p[i - 1] + (1 << l)) % n]};
pii cur = {c[p[i]], c[(p[i] + (1 << l)) % n]};
if (prv != cur)
cl++;
cn[p[i]] = cl - 1;
}
c.swap(cn);
}
return p;
}
vector<int> suffix_nxtay(string &S) {
S += '#';
vector<int> p = sort_cyclic_shift(S);
S.pop_back();
p.erase(p.begin());
return p;
}
vector<int> cal_lcp(vector<int> &p, string &S) {
int n = S.size();
vector<int> rank(n);
for (int i = 0; i < n; i++)
rank[p[i]] = i;
vector<int> lcp(n - 1);
int k = 0;
for (int i = 0; i < n; i++) {
if (rank[i] == n - 1) {
k = 0;
continue;
}
int j = p[rank[i] + 1];
while (i + k < n && j + k < n && S[i + k] == S[j + k])
k++;
lcp[rank[i]] = k;
if (k)
k--;
}
return lcp;
}
struct node {
vector<int> vec;
vector<int> cnt;
int l, r;
};
const int maxN = 10000;
const int maxL = 1e6 + 100;
string t[maxN];
bool mark[maxL];
int nxt[maxL];
int cnt[maxL];
pii seg[maxL << 2];
void build(int id, int L, int R) {
if (L + 1 == R) {
seg[id] = pii(nxt[L], L);
return;
}
int mid = (L + R) >> 1;
build(id << 1 | 0, L, mid);
build(id << 1 | 1, mid, R);
seg[id] = max(seg[id << 1], seg[id << 1 | 1]);
}
pii getmax(int id, int L, int R, int l, int r) {
if (L == l && R == r) {
return seg[id];
}
pii ans = {0, 0};
int mid = (L + R) >> 1;
if (l < mid)
ans = max(ans, getmax(id << 1 | 0, L, mid, l, min(mid, r)));
if (r > mid)
ans = max(ans, getmax(id << 1 | 1, mid, R, max(l, mid), r));
return ans;
}
const int maxlg = 20;
int par[maxL][maxlg];
int main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, m;
cin >> n >> m;
for (int i = 0; i < n; i++) {
cin >> t[i];
}
string S;
cin >> S;
int L = S.size();
for (int i = 0; i < n; i++) {
S += '$';
mark[(int)S.size()] = true;
S += t[i];
}
vector<int> p = suffix_nxtay(S);
vector<int> lcp = cal_lcp(p, S);
lcp.pb(0);
int tmp = 0;
for (int i = 0; i < p.size(); i++) {
if (mark[p[i]]) {
tmp = lcp[i];
} else {
nxt[p[i]] = tmp + p[i];
tmp = min(tmp, lcp[i]);
}
}
tmp = 0;
for (int i = p.size() - 1; i >= 0; i--) {
if (mark[p[i]]) {
if (i > 0)
tmp = lcp[i-1];
} else {
nxt[p[i]] = max(nxt[p[i]], tmp + p[i]);
nxt[p[i]] = min(L, nxt[p[i]]);
}
if (i > 0)
tmp = min(tmp, lcp[i-1]);
}
nxt[L] = L;
build(1, 0, L +1);
for (int i = 0; i <= L; i++) {
int p = getmax(1, 0, L +1, i, min(nxt[i] + 1, L +1)).second;
par[i][0] = (p == i ? L + 1 : p);
}
par[L + 1][0] = L + 1;
for (int i = 1; i < maxlg; i++) {
for (int j = 0; j <= L + 1; j++) {
par[j][i] = par[par[j][i - 1]][i - 1];
}
}
while (m--) {
int l, r;
cin >> l >> r;
int ans = 0, v = l;
for (int i = maxlg - 1; i >= 0; i--) {
if (par[v][i] < r) {
ans += (1 << i);
v = par[v][i];
}
}
if (nxt[v] < r) {
cout << -1 << endl;
continue;
}
if (ans == 0) {
cout << 1 << endl;
continue;
}
int d = ans - 1;
v = l;
for (int i = 0; i < maxlg; i++) {
if (d >> i & 1) {
v = par[v][i];
}
}
cout << ans + (nxt[v] < r) << endl;
}
}
