#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, temp;
  cin >> n;
  map<int, int> a, b;
  for (int i = 0; i < n; i++) {
    cin >> temp;
    a[temp]++;
  }
  for (int i = 0; i < n; i++) {
    cin >> temp;
    b[temp]++;
  }
  int ans = 0, sum = 0;
  vector<int> bal(6);
  for (int i = 1; i < 6; i++) {
    if ((a[i] + b[i]) % 2) {
      cout << -1;
      return 0;
    }
    bal[i] = a[i] - b[i];
    bal[i] /= 2;
    sum += bal[i];
    if (bal[i] > 0) ans += bal[i];
  }
  if (sum) {
    cout << -1;
    return 0;
  }
  cout << abs(ans);
  return 0;
}
