#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

const LL LINF = 1e18;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n, m;
	cin >> n >> m;
	vector<LL> dp(n + 2, LINF);
	FOR(i, 1, m + 1) {
		dp[i] = 0;
	}
	FOR(i, 1, n + 1) {
		int cost;
		cin >> cost;
		dp[i] += cost;
		FOR(j, 1, min(m, n - i + 1) + 1) {
			int c;
			cin >> c;
			dp[i + j] = min(dp[i + j], dp[i] - c);
		}
	}
	cout << dp[n + 1] << "\n";
	return 0;
}