#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n;
  cin >> m;
  vector<long long> a(n);
  vector<long long> b(m);
  long long max = 0, min = -1;
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (max < a[i]) max = a[i];
    sum = sum + a[i] * (long long)m;
  }
  long long sum1 = 0;
  for (int j = 0; j < m; j++) {
    cin >> b[j];
    sum1 = sum1 + b[j];
    if (min == -1 || min > b[j]) min = b[j];
  }
  if (max > min) {
    cout << "-1\n";
    return 0;
  }
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  long k1 = 0;
  for (int i = 0; i < m; i++) {
    if (a[a.size() - 1] == b[i]) {
      k1 = 1;
      break;
    }
  }
  if (k1 == 1) {
    sum = sum - a[a.size() - 1] * (long long)m;
    sum = sum + sum1;
  } else {
    sum = sum - a[a.size() - 1] * (long long)m;
    sum = sum + a[a.size() - 1];
    sum = sum + sum1;
    sum = sum - a[a.size() - 2];
  }
  cout << sum << "\n";
  return 0;
}
