#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
int op(int a, int b) { return a + b; }
int e() { return 0; }
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int m, k; cin >> m >> k;
	vector<int>v(m * k);
	vector<vector<int>>pos(m);
	rep(i, m*k) {
		int a; cin >> a;
		pos[a].push_back(i);
	}
	rep(i, m) {
		rep(j, k) {
			int idx = m * j + i;
			v[idx] = pos[i][j];
		}
	}
	long long memo = 0;
	{
		segtree<int, op, e>seg(m * k);
		rep(i, v.size()) {
			memo += seg.prod(v[i], m * k);
			seg.set(v[i], 1);
		}
	}
	long long ans = memo;
	vector<int>v2(m * k);
	rep(i, k) {
		//set<int>st;
		vector<int>vec;
		rep(j, m) {
			int idx = i * m + j;
			//st.insert(v[idx]);
			vec.push_back(v[idx]);
		}
		sort(all(vec));
		rep(j, m) {
			int idx = i * m + j;
			//v2[idx] = st.lower_bound(v[idx]) - st.begin();
			v2[idx] = lower_bound(all(vec), v[idx]) - vec.begin();
		}
	}
	//rep(i, v2.size())cout << v2[i] << " ";
	//cout << endl;
	rep(i, m - 1) {
		rep(j, k) {
			int idx = m * j + i;
			int x = v2[idx];
			memo -= x;
			memo += (m - 1) - x;
		}
		chmin(ans, memo);
	}
	cout << ans << endl;
	return 0;
}