package InfinityJune21.HackathonDoubtSessionJul4;

import java.util.Arrays;

import java.util.Scanner;

public class KillTheMonster {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

int N = scanner.nextInt();

int D = scanner.nextInt();

int H = scanner.nextInt();

int attackWeight[][] = new int[2][N];

for(int i = 0; i < N; i++) {

attackWeight[0][i] = scanner.nextInt();

}

for(int i = 0; i < N; i++) {

int weight = scanner.nextInt();

if(weight > D) {

attackWeight[0][i] = 0;

attackWeight[1][i] = 0;

}

else {

//totalAttackingPower = totalAttackingPower + attackWeight[0][i];

attackWeight[1][i] = weight;

}

}

Arrays.sort(attackWeight[0]);

int weaponsCount = 0;

int attackingPowerReached = 0;

for(int i = attackWeight[0].length - 1; i >= 0 ; i--) {

if(attackWeight[0][i] > 0) {

attackingPowerReached = attackingPowerReached + attackWeight[0][i];

weaponsCount = weaponsCount + 1;

if(attackingPowerReached >= H) {

break;

}

}

}

if(attackingPowerReached >= H) {

System.out.println(weaponsCount);

}

else {

System.out.println("-1");

}

}

}