#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define forn(i,n) for(int i=0;i<n;i++)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(),v.rend()
#define pb push_back
#define sz(a) (int)a.size()
int minimumInstructions(int n, int m, int k, vector<int> c, vector<int> a, vector<vector<int>> b) {
vector<int> p[k + 1];
map<pair<int, int>, int> mx;
for(int i = 0; i < m; ++i) {
for(auto x: b[i]) {
p[x].pb(i);
}
}
for(int i = n - 1; i >= 0; --i) {
for(auto x: p[c[i]]) {
mx[{x, i}] = max(mx[{x, i}], mx[{(x + 1) % m, i + 1}] + 1);
}
}
vector<bool> can(n, false);
for(int i = 0; i < n; ++i) {
for(auto x: p[c[i]]) {
if(mx[{x, i}] >= m) can[i] = true;
}
}
set<int> good;
forn(i, n) if(can[i]) good.insert(i);
if(good.empty()) return -1;
if(!can[0]) return -1;
int lst = -100000000, ans = 0;
for(int i = 0; i < n; ++i) {
if(lst + m - 1 >= i) continue;
++ans;
if(can[i]) {
lst = i;
} else {
auto it = good.lower_bound(i);
if(it == good.begin()) return -1;
--it;
if(*it + m - 1 < i) return -1;
lst = *it;
}
}
return ans;
}
/*
void solve() {
int n, m, k; cin >> n >> m >> k;
vector<int> c(n); forn(i, n) cin >> c[i];
vector<int> a(m); forn(i, m) cin >> a[i];
vector<vector<int>> b(m);
for(int i = 0; i < m; ++i) {
b[i].resize(a[i]);
for(int j = 0; j < a[i]; ++j) {
cin >> b[i][j];
}
}
cout << minimumInstructions(n, m, k, c, a, b) << "\n";
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int t = 1;
//cin >> t;
while(t--) {
solve();
}
}
*/
