#include<bits/stdc++.h>
using namespace std;
const long long maxn=500000+10;
vector<pair<long long ,long long>>allv[maxn];
long long mp[maxn],base=131,mod=2000000357,ps[maxn],maxa[maxn],sz,rev[maxn];
long long m,n;
string s;
long long lca[20][maxn];
long long mod2=1e9+7,mp2[maxn],rev2[maxn],ps2[maxn];
long long mypow2(long long m,long long y){
if(y==0){
return 1;
}
long long p=mypow2(m,(y>>1));
p*=p;
p%=mod2;
if(y&1){
p*=m;
p%=mod2;
}
return p;
}
long long mypow(long long m,long long y){
if(y==0){
return 1;
}
long long p=mypow(m,(y>>1));
p*=p;
p%=mod;
if(y&1){
p*=m;
p%=mod;
}
return p;
}
void aval(){
mp[0]=1;
for(long long i=1;i<maxn;i++){
mp[i]=1ll*mp[i-1]*base%mod;
}
rev[maxn-1]=mypow(mp[maxn-1],mod-2);
for(long long i=maxn-2;i>=0;i--){
rev[i]=1ll*rev[i+1]*base%mod;
}
mp2[0]=1;
for(long long i=1;i<maxn;i++){
mp2[i]=1ll*mp2[i-1]*base%mod2;
}
rev2[maxn-1]=mypow2(mp2[maxn-1],mod2-2);
for(long long i=maxn-2;i>=0;i--){
rev2[i]=1ll*rev2[i+1]*base%mod2;
}
}
long long ww2(long long a){
if(a>=mod2){
a-=mod2;
}
return a;
}
long long ww(long long a){
if(a>=mod){
a-=mod;
}
return a;
}
long long pors2(long long l,long long r){
r++;
l++;
long long ret=ps2[r]-ps2[l-1]+mod2;
ret=ww2(ret);
ret=1ll*ret*rev2[l-1]%mod2;
return ret;
}
long long pors(long long l,long long r){
r++;
l++;
long long ret=ps[r]-ps[l-1]+mod;
ret=ww(ret);
ret=1ll*ret*rev[l-1]%mod;
return ret;
}
long long exi(long long lev,pair<long long,long long>w){
long long p=lower_bound(allv[lev].begin(),allv[lev].end(),w)-allv[lev].begin();
if(p==(long long)allv[lev].size()||allv[lev][p]!=w){
return 0;
}
return 1;
}
void callca(){
for(long long j=1;j<maxn;j++){
if(lca[0][j]==0){
lca[0][j]=-1;
}
}
for(long long i=1;i<20;i++){
for(long long j=0;j<maxn;j++){
if(lca[i-1][j]==-1){
lca[i][j]=-1;
continue;
}
lca[i][j]=lca[i-1][lca[i-1][j]];
}
}
}
void solve(long long l,long long r){
r--;
long long res=1;
if(maxa[l]>=r){
cout<<1<<"\n";
return ;
}
for(long long i=19;i>=0;i--){
if(lca[i][l]==-1||maxa[lca[i][l]]<lca[i][l]){
continue;
}
if(maxa[lca[i][l]]>=r){
continue;
}
res+=(1<<i);
// cout<<"ha: "<<l<<" "<<i<<" "<<lca[i][l]<<"\n";
l=lca[i][l];
}
res++;
l=lca[0][l];
//cout<<l<<" "<<maxa[l]<<" "<<res<<"\n";
if(l==-1||maxa[l]<r){
cout<<-1<<"\n";
return ;
}
cout<<res<<"\n";
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
aval();
//freopen("inp.txt","r",stdin);
//freopen("out.txt","w",stdout);
cin>>n>>m;
for(long long i=0;i<n;i++){
cin>>s;
long long unnow=0,unnow2=0;
for(long long j=0;j<(long long)s.size();j++){
unnow+=1ll*s[j]*mp[j]%mod;
unnow=ww(unnow);
unnow2+=1ll*s[j]*mp2[j]%mod2;
unnow2=ww2(unnow2);
allv[j+1].push_back(make_pair(unnow,unnow2));
}
}
for(long long i=0;i<maxn;i++){
sort(allv[i].begin(),allv[i].end());
allv[i].resize(unique(allv[i].begin(),allv[i].end())-allv[i].begin());
}
cin>>s;
long long unnow=0,unnow2=0;
sz=(long long)s.size();
for(long long j=0;j<(long long)s.size();j++){
unnow+=1ll*s[j]*mp[j]%mod;
unnow=ww(unnow);
unnow2+=1ll*s[j]*mp2[j]%mod2;
unnow2=ww2(unnow2);
ps[j+1]=unnow;
ps2[j+1]=unnow2;
}
for(long long i=0;i<sz;i++){
long long low=i-1,high=sz,mid;
while(high-low>1){
mid=(high+low)>>1;
if(exi(mid-i+1,make_pair(pors(i,mid),pors2(i,mid)))){
low=mid;
}
else{
high=mid;
}
}
maxa[i]=low;
//<<i<<" dsa "<<maxa[i]<<"\n";
}
deque<pair<long long,long long>>v;
v.push_back(make_pair(sz,sz+2));
for(long long i=sz-1;i>=0;i--){
long long p=lower_bound(v.begin(),v.end(),make_pair(maxa[i]+2,-1ll))-v.begin();
p--;
if(p<0){
v.push_front(make_pair(i,maxa[i]));
lca[0][i]=-1;
continue;
}
lca[0][i]=v[p].first;
while((long long)v.size()>0&&v.front().second<=maxa[i]){
v.pop_front();
}
v.push_front(make_pair(i,maxa[i]));
}
callca();
for(long long i=0;i<m;i++){
long long l,r;
cin>>l>>r;
solve(l,r);
}
}
