#include <bits/stdc++.h>
using namespace std;
const int X = 1e5 + 9;
const long long inf = (1ll << 60);
int n, sum, a[109], b[109], c[109];
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    b[a[i]]++;
  }
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    c[a[i]]++;
  }
  for (int i = 1; i <= 5; i++) {
    if ((b[i] + c[i]) % 2 == 1) {
      puts("-1");
      return 0;
    }
  }
  for (int i = 1; i <= 5; i++) {
    sum += (abs(c[i] - b[i]) / 2);
  }
  cout << sum / 2 << endl;
}
