import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int[] petrol = new int[n];
        int[] distance = new int[n];
        for(int i = 0; i<n; i++) {
            petrol[i] = scanner.nextInt();
        }
        for(int i = 0; i<n; i++) {
            distance[i] = scanner.nextInt();
        }

        int prevPetrol = 0, currPetrol = 0, start = 0;
        for(int i = 0; i<n; i++) {
            currPetrol += petrol[i] - distance[i];
            if(currPetrol < 0) {
                prevPetrol += currPetrol;
                start = i + 1;
                currPetrol = 0;
            }
        }

        if(start < n && currPetrol + prevPetrol >= 0) {
            System.out.println(start);
            return;
        }
        System.out.println(-1);
    }
}