#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<vector>
#include<list>
#include<algorithm>
#include<utility>
#include<complex>
#include<functional>
using namespace std;
#define LL long long

#define V 50
#define E 1500
#define M 301
LL dp[V][M];
const LL INF = 1e9;
LL from[E], to[E], tim[E], cost[E];
LL v, m, e;

void solve(){
	for (int i = 0; i < V; i++)
		for (int j = 0; j < M; j++)dp[i][j] = INF;
	dp[0][0] = 0;
	for (int i = 0; i < 51; i++){
		for (int j = 0; j < e; j++){
			for (LL k = cost[j]; k <= m; k++)
				dp[to[j]][k] = min(dp[to[j]][k], dp[from[j]][k - cost[j]] + tim[j]);
		}
	}


}
int main(void){
	cin >> v >> m >> e;
	v--;
	for (int i = 0; i < e; i++){ cin >> from[i]; from[i]--; }
	for (int i = 0; i < e; i++){ cin >> to[i]; to[i]--; }
	for (int i = 0; i < e; i++)cin >> cost[i];
	for (int i = 0; i < e; i++)cin >> tim[i];
	solve();
	LL res = INF;
	for (int i = 0; i <= m; i++)
		res = min(res, dp[v][i]);
	cout << ((res==INF)?-1:res) << endl;
	return 0;
}