#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include<cstdint>
#include<cstddef>
#include<vector>
//#include<atcoder/all>
//using namespace atcoder;
using namespace std;
using i32 = int_fast32_t;
using i64 = int_fast64_t;
using usize = size_t;
using u32 = uint_fast32_t;
using u64 = uint_fast64_t;
using i128 = __int128_t;
using u128 = __uint128_t;
template<typename T>
using vec = vector<T>;
#define rep(i, n) for (i64 i = 0; i < (i64)(n); ++i)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define len(hoge) (i64)((hoge).size())
using P = pair<i64,i64>;
void solve(){
}
int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    i64 n;
    cin >> n;
    i64 sum_a = 0,sum_b = 0;
    vec<i64> a(n),b(n);
    rep(i,n){
        cin >> a[i];
        sum_a += a[i];
    }
    rep(i,n){
        cin >> b[i];
        sum_b += b[i];
    }
    if(a == b){
        cout << 0 << endl;
        return 0;
    }
    if((sum_a - sum_b) > 0 && (sum_a - sum_b) % 2 == 0){
        cout << (sum_a - sum_b) / 2 << endl;
    }else{
        cout << -1 << endl;
    }
}