#include <bits/stdc++.h>
using namespace std;
#define int long long
#define inf 0x3F3F3F3F3F3F3F3F
const int MXN = 1e6 + 5;
const int LOG = 20;
const int mod = 1000000000000000009;
const int base = 9128398;
int ph[2][MXN], p[MXN], invp[MXN];
int mult(int a, int b)
{
return ((__int128)a * (__int128)b) % mod;
}
int add(int a, int b)
{
return ((__int128)a + (__int128)b + (__int128)mod) % mod;
}
int pw(int a, int b, int c)
{
a %= c;
int res = 1;
while (b)
{
if (b & 1) res = mult(res, a);
a = mult(a, a);
b >>= 1;
}
return res;
}
int get_hash(int l, int r, int id)
{
return mult(add(ph[id][r], mod - ph[id][l - 1]), invp[l]);
}
void _HASH(string &s, int id)
{
int n = (int)s.length() - 1;
ph[id][0] = 0;
for (int i = 1; i <= n; i++) ph[id][i] = add(ph[id][i - 1], mult(p[i], s[i] - 'a' + 1));
}
array<int, 2> st[MXN << 2];
int par[LOG][MXN];
void make(int l, int r, int x, int ind, int val)
{
if (l == r)
{
st[x] = {val, ind};
return;
}
int mid = (l + r) >> 1;
if (ind <= mid) make(l, mid, 2*x, ind, val);
else make(mid + 1, r, 2*x + 1, ind, val);
st[x] = max(st[2*x], st[2*x + 1]);
}
array<int, 2> get(int l, int r, int x, int lx, int rx)
{
if (l > rx || r < lx) return {0, 0};
if (l >= lx && r <= rx) return st[x];
int mid = (l + r) >> 1;
return max(get(l, mid, 2*x, lx, rx), get(mid + 1, r, 2*x + 1, lx, rx));
}
int L, n, k;
string t[MXN], s;
set<int> mp[MXN];
int nxt[MXN];
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
p[0] = 1;
for (int i = 1; i < MXN; i++) p[i] = mult(p[i - 1], base);
for (int i = 0; i < MXN; i++) invp[i] = pw(p[i], mod - 2, mod);
cin >> n >> k;
for (int i = 0; i < n; i++) cin >> t[i];
cin >> s;
L = s.length();
s = "#" + s;
_HASH(s, 0);
for (int i = 0; i < n; i++)
{
t[i] = "#" + t[i];
_HASH(t[i], 1);
for (int j = 1; j < t[i].length(); j++) mp[j].insert(get_hash(1, j, 1));
}
for (int i = 1; i <= L; i++)
{
if (mp[1].find(get_hash(i, i, 0)) == mp[1].end()) nxt[i] = 0;
else
{
int l = i, r = L;
while (l < r)
{
int mid = (l + r + 1) >> 1;
if (mp[mid - i + 1].find(get_hash(i, mid, 0)) != mp[mid - i + 1].end()) l = mid;
else r = mid - 1;
}
nxt[i] = l + 1;
}
}
for (int i = 1; i <= L; i++) if (nxt[i]) make(1, L, 1, i, nxt[i]);
for (int i = 1; i <= L; i++)
{
array<int, 2> j = get(1, L, 1, i, nxt[i]);
if (j[0] > nxt[i])
{
par[0][i] = j[1];
}
}
for (int i = 1; i < LOG; i++) for (int j = 1; j <= L; j++) par[i][j] = par[i - 1][par[i - 1][j]];
while (k--)
{
int l, r, res = 0;
cin >> l >> r;
l++;
if (nxt[l] > r)
{
cout << 1 << '\n';
continue;
}
for (int i = LOG - 1; i >= 0; i--)
{
if (!par[i][l] || nxt[par[i][l]] > r) continue;
l = par[i][l];
res |= (1LL << i);
}
if (nxt[par[0][l]] > r) cout << res + 2 << '\n';
else cout << -1 << '\n';
}
}
