#include<bits/stdc++.h>
#include<fstream>
#pragma GCC optimize("O3")
#pragma GCC target("avx2")
using namespace std;
#define sz(a) (int)a.size()
#define ALL(v) v.begin(), v.end()
#define ALLR(v) v.rbegin(), v.rend()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define mpp make_pair
const ld PI = 3.14159265359, prec = 1e-9;;
//using u128 = __uint128_t;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, -1, 0, 1};
const ll mod = 1e9 + 7, pr = 31;
const int mxn = 2e5 + 5, mxd = 250 * 250, sq = 100, mxv = 5e4 + 1, mxq = 2e6 + 5, T = 1000;
//const int base = (1 <<18);
const ll inf = 2e9 + 5, neg = -69420, inf2 = 1e14;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
#include "paint.h"
#include <vector>
int n, m, k;
bool ok[mxn + 1];
int cnt[50005], last[50005], c[mxn + 1], dp[mxn + 1];
vt<int>comp[mxn + 1];
int minimumInstructions(int N, int M, int K, std::vector<int> C, std::vector<int> A, std::vector<std::vector<int>> B) {
n = N; m = M; k = K;
for(int i = 1; i <= n; i++){
c[i] = C[i - 1];
}
for(int i = 0; i < m; i++){
for(auto j: B[i]){
comp[j].pb(i);
}
}
for(int i = 1; i <= n; i++)dp[i] = inf;
deque<int>dq; dq.pb(0);
for(int i = 1; i <= n; i++){
while(sz(dq) && dq.front() + m < i)dq.pop_front();
for(auto j: comp[c[i]]){
int coef = (i - j + m) % m;
if(last[coef] == i - 1){
last[coef] = i; cnt[coef]++;
}else{
last[coef] = i; cnt[coef] = 1;
}
if(cnt[coef] >= m){
dp[i] = min(dp[i], dp[dq.front()] + 1);
}
}
while(sz(dq) && dp[i] <= dp[dq.back()])dq.pop_back();
dq.pb(i);
}
if(dp[n] == inf)dp[n] = -1;
return(dp[n]);
}
/*
int main() {
int N, M, K;
assert(3 == scanf("%d %d %d", &N, &M, &K));
std::vector<int> C(N);
for (int i = 0; i < N; ++i) {
assert(1 == scanf("%d", &C[i]));
}
std::vector<int> A(M);
std::vector<std::vector<int>> B(M);
for (int i = 0; i < M; ++i) {
assert(1 == scanf("%d", &A[i]));
B[i].resize(A[i]);
for (int j = 0; j < A[i]; ++j) {
assert(1 == scanf("%d", &B[i][j]));
}
}
int minimum_instructions = minimumInstructions(N, M, K, C, A, B);
printf("%d\n", minimum_instructions);
return 0;
}
*/
