#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;

#define REP(i,n) for(long long i = 0; i < (n); i++)
#define FOR(i, m, n) for(long long i = (m);i < (n); ++i)
#define ALL(obj) (obj).begin(),(obj).end()
#define SPEED cin.tie(0);ios::sync_with_stdio(false);

template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;

const ll MOD = (ll)1e9 + 7;
const ll MOD2 = 998244353;
const ll HIGHINF = (ll)1e18;
const ll LOWINF = (ll)1e15;
const long double PI = 3.1415926535897932384626433;

template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template <class T, class U>ostream &operator<<(ostream &o, const map<T, U>&obj) {o << "{"; for (auto &x : obj) o << " {" << x.first << " : " << x.second << "}" << ","; o << " }"; return o;}
template <class T>ostream &operator<<(ostream &o, const set<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const multiset<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const vector<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T, class U>ostream &operator<<(ostream &o, const pair<T, U>&obj) {o << "{" << obj.first << ", " << obj.second << "}"; return o;}
template <template <class tmp>  class T, class U> ostream &operator<<(ostream &o, const T<U> &obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr)o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
void print(void) {cout << endl;}
template <class Head> void print(Head&& head) {cout << head;print();}
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) {cout << head << " ";print(forward<Tail>(tail)...);}
template <class T> void chmax(T& a, const T b){a=max<T>(a,b);}
template <class T> void chmin(T& a, const T b){a=min<T>(a,b);}
void YN(bool flg) {cout << ((flg) ? "YES" : "NO") << endl;}
void Yn(bool flg) {cout << ((flg) ? "Yes" : "No") << endl;}
void yn(bool flg) {cout << ((flg) ? "yes" : "no") << endl;}

int main() {
    while(1){
        int N,M; cin >> N >> M;
        if(N==0&&M==0) return 0;

        V<ll> c(160,0);
        V<V<ll>> a(160,V<ll>(10,0)),b(160,V<ll>(10,0));
        V<V<V<ll>>> dp(160,V<V<ll>>(10,V<ll>(100,LOWINF)));
        
        for(int i = 0; i < N; ++i){
            cin >> c[i];
            for(int j = 0; j < c[i]; ++j){
                cin >> a[i][j] >> b[i][j];
            }
        }

        for(int j = 0; j < c[0]; ++j) dp[0][j][0] = 0;
        for(int j = 0; j < c[1]; ++j) dp[1][j][1] = 0;
        
        for(int i = 0; i < N; ++i){

            for(int j = 0; j < c[i]; ++j){
                for(int k = 0; k < c[i+1]; ++k){
                    ll cost = abs(a[i][j]-a[i+1][k])*(b[i][j]+b[i+1][k]);
                    for(int n = 0; n <= M; ++n){
                        chmin(dp[i+1][k][n],dp[i][j][n]+cost);
                    }
                }
            }

            for(int j = 0; j < c[i]; ++j){
                for(int k = 0; k < c[i+2]; ++k){
                    ll cost = abs(a[i][j]-a[i+2][k])*(b[i][j]+b[i+2][k]);
                    for(int n = 0; n <= M; ++n){
                        chmin(dp[i+2][k][n+1],dp[i][j][n]+cost);
                    }
                }
            }

        }

        ll ans = LOWINF;
        for(int n = 0; n <= M; ++n) for(int j = 0; j < c[N-1]; ++j) chmin(ans,dp[N-1][j][n]);
        for(int n = 0; n < M; ++n) for(int j = 0; j < c[N-2]; ++j) chmin(ans,dp[N-2][j][n]);

        cout << ans << endl;    
    }
    return 0;
}



Measured memory_bytes: 4232