#ifdef t9unkubj
#include"debug.cpp"
//#include"template_no_debug.h"
#else
#define dbg(...) 199958
#endif
#undef _GLIBCXX_DEBUG
#pragma GCC optimize("O3")
using namespace std;
#include<bits/stdc++.h>
using ll=long long;
using ull=unsigned long long;
template<class T>using vc=vector<T>;
template<class T>using vvc=vc<vc<T>>;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define REP(i,j,n) for(ll i=(j);i<(ll)(n);i++)
#define DREP(i,n,m) for(ll i=(n);i>=(m);i--)
#define drep(i,n) for(ll i=((n)-1);i>=0;i--)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
template<class T,class F>
bool chmin(T &x, F y){
if(x>y){
x=y;
return true;
}
return false;
}
template<class T, class F>
bool chmax(T &x, F y){
if(x<y){
x=y;
return true;
}
return false;
}
double pass_time=0;
int solve(int n,int m,int k,vc<int>c,vc<int>a,vvc<int>b){
vvc<int>cols(n);
rep(i,m){
for(auto&x:b[i]){
cols[x].push_back(i);
}
}
vc<int>ok_cnt((n+m)*2);
vc<int>ok(n-m+1);
int yoi=0;
int OFFSET=n+m;
auto F=[&](int i,int coef){
for(auto&x:cols[c[i]]){
if(coef==1){
ok_cnt[(-i+x)+OFFSET]++;
if(ok_cnt[(-i+x)+OFFSET]==m){
yoi++;
}
ok_cnt[(-(i+m)+x)+OFFSET]++;
if(ok_cnt[(-(i+m)+x)+OFFSET]==m){
yoi++;
}
}else{
if(ok_cnt[(-i+x)+OFFSET]==m){
yoi--;
}
ok_cnt[(-i+x)+OFFSET]--;
if(ok_cnt[(-(i+m)+x)+OFFSET]==m){
yoi--;
}
ok_cnt[(-(i+m)+x)+OFFSET]--;
}
}
};
rep(i,m){
F(i,1);
}
ok[0]=!!yoi;
REP(i,m,n){
F(i-m,-1);
F(i,1);
ok[i-m+1]=!!yoi;
}
if(!ok[0])return -1;
dbg(ok);
set<int>st;
rep(i,n-m+1)if(ok[i])st.insert(i);
int ans=1;
int now=0;
while(1){
auto it=st.upper_bound(now+m);
if(it==st.begin())return -1;
it=prev(it);
if(*it<=now)return -1;
now=*it;
++ans;
if(now==n-m)break;
}
return ans;
}
int minimumInstructions(
int N, int M, int K, std::vector<int> C,
std::vector<int> A, std::vector<std::vector<int>> B) {
return solve(N,M,K,C,A,B);
}
namespace judge{
void run(){
int n,m,k;
cin>>n>>m>>k;
vc<int>c(n);
rep(i,n)cin>>c[i];
vc<int>a(m);
vvc<int>b(m);
rep(i,m){
cin>>a[i];
b[i].resize(a[i]);
rep(j,a[i])cin>>b[i][j];
}
dbg(solve(n,m,k,c,a,b));
}
};
//int main(){judge::run();}
//g++ paint.cpp -D t9unkubj
