/* @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_array(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) {
continue;
k = 0;
}
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;
}
const int maxN = 10000;
const int maxL = 1e6 + 100;
const int K = 550;
string t[maxN];
bool mark[maxL];
int arr[maxL];
int nxt[maxL];
int cnt[maxL];
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_array(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 {
arr[p[i]] = tmp;
}
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 {
arr[p[i]] = max(arr[p[i]], tmp);
}
if (i > 0)
tmp = min(tmp, lcp[i-1]);
}
for (int i = L - 1; i >= 0; i--) {
if (arr[i] == 0) {
nxt[i] = -1;
continue;
}
int j = i + arr[i];
if (j / K != i / K || j >= L) {
nxt[i] = min(j, L);
cnt[i] = 1;
} else {
nxt[i] = nxt[j];
cnt[i] = cnt[j] + 1;
}
}
for (int i = 0; i < m; i++) {
int l, r;
cin >> l >> r;
r--;
bool flag = false;
int ans = 0;
int gl = l / K;
int gr = r / K;
while (gl < gr) {
ans += cnt[l];
l = nxt[l];
if (l == -1) {
flag = true;
break;
}
gl = l / K;
}
while (!flag && l <= r) {
if (arr[l] == 0) {
flag = true;
break;
}
l += arr[l];
ans++;
}
if (flag) {
cout << -1 << endl;
} else {
cout << ans << endl;
}
}
}
