#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << " " << H;
debug_out(T...);
}
#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
#define F first
#define S second
const int maxn = 500 + 10;
const int maxa = 5e5 + 10;
const int inf = 1e9;
const int alpha = 26;
int n, q, dp[maxn][maxn], trie[maxa][alpha], vercnt;
string s;
void add(string &s){
int v = 0;
for (auto c: s){
int x = c - 'a';
if (trie[v][x] == -1) trie[v][x] = ++vercnt;
v = trie[v][x];
}
}
bool find(int l, int r){
int v = 0;
for (int i = l; i <= r; i++){
int x = s[i] - 'a';
if (trie[v][x] == -1) return false;
v = trie[v][x];
}
return true;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
memset(trie, -1, sizeof trie);
cin >> n >> q;
for (int i = 1; i <= n; i++){
string s; cin >> s;
add(s);
}
cin >> s;
int sz = s.size();
for (int i = sz-1; ~i; i--){
for (int j = i; j < sz; j++){
dp[i][j] = inf;
if (find(i, j)){
dp[i][j] = 1;
continue;
}
for (int k = i; k < j; k++){
dp[i][j] = min(dp[i][j], dp[i][k] + dp[k+1][j]);
}
}
}
while(q--){
int l, r; cin >> l >> r;
cout << (dp[l][r-1] == inf? -1: dp[l][r-1]) << '\n';
}
return 0;
}
