#include <bits/stdc++.h>
using namespace std;
long long a[300010], b[300010];
int main() {
  long long n, m;
  while (cin >> n >> m) {
    long long sum = 0;
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      sum += a[i];
    }
    sum *= m;
    sort(a, a + n);
    for (int j = 0; j < m; j++) {
      cin >> b[j];
      sum += b[j];
    }
    sort(b, b + m);
    if (b[0] < a[n - 1])
      cout << -1 << endl;
    else {
      if (b[0] == a[n - 1])
        sum = sum - m * a[n - 1];
      else
        sum = sum - (m - 1) * a[n - 1] - a[n - 2];
      cout << sum << endl;
    }
  }
  return 0;
}
