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

int main() {
	int N,M;
	cin >> N;
	vector<int> A(N);
	map<int,int> C;
	for(int i =0; i < N; i++) {
		cin >> A[i];
		C[A[i]] +=1;}
	if(C.size() == 1) {cout << "0\n"; return 0;}
	cin >> M;
	for(int i =0; i < M; i++) {
		int x,y;
		cin >> x >> y;
		x--;
		C[A[x]] -=1;
		C[y] +=1;
		A[x] =y;
		if(C[y] == N) {cout << i+1 << "\n"; return 0;}
		}
	cout << "-1\n";
	return 0;}