#include "bits/stdc++.h"
using namespace std;
#define int long long
#define REP(i, n) for (int i = 0; i < (int)n; ++i)
#define RREP(i, n) for (int i = (int)n - 1; i >= 0; --i)
#define FOR(i, s, n) for (int i = s; i < (int)n; ++i)
#define RFOR(i, s, n) for (int i = (int)n - 1; i >= s; --i)
#define ALL(a) a.begin(), a.end()
#define IN(a, x, b) (a <= x && x < b)
template<class T>inline void out(T t){cout << t << "\n";}
template<class T,class... Ts>inline void out(T t,Ts... ts){cout << t << " ";out(ts...);}
template<class T>inline bool CHMIN(T&a,T b){if(a > b){a = b;return true;}return false;}
template<class T>inline bool CHMAX(T&a,T b){if(a < b){a = b;return true;}return false;}
constexpr int INF = 1e18;



signed main(){
	int N;
	cin >> N;
	vector<int>a(N), b(N);
	REP(i, N) {
		cin >> a[i];
	}
	REP(i, N) {
		cin >> b[i];
	}
	int x = accumulate(ALL(a), 0ll) - accumulate(ALL(b), 0ll);
	if(N == 2) {
		if(x == 0) out(abs(a[0] - b[0]));
		else out(-1);
		return 0;
	}
	if(x < 0 || x % (N - 2)) {
		out(-1);
		return 0;
	}
	x /= N - 2;
	int ans = x;
	int minus = 0;
	vector<tuple<int,int,int>>v(N);
	REP(i, N) {
		v[i] = {a[i] - b[i], a[i], b[i]};
	}
	sort(ALL(v));
	REP(i, N) {
		auto[hoge, A, B] = v[i];
		a[i] = A;
		b[i] = B;
	}
	REP(i, N) {
		a[i] -= minus;
		int t = (b[i] - a[i] + x);
		if(t < 0 || t % 2) {
			//out(i,"aaa");
			out(-1);
			return 0;
		}
		t /= 2;
		minus += t;
		x = x - t;
	}
	out(ans);
}