#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  long long rmax, cmin, x, rmax2, rsum, csum, ans;
  cin >> n >> m;
  rmax = 0;
  rmax2 = 0;
  rsum = 0;
  for (int i = 0; i < n; i++) {
    cin >> x;
    if (rmax <= x) {
      rmax2 = rmax;
      rmax = x;
    } else if (rmax2 <= x)
      rmax2 = x;
    rsum += x;
  }
  cmin = INT_MAX;
  csum = 0;
  for (int i = 0; i < m; i++) {
    cin >> x;
    if (cmin >= x) cmin = x;
    csum += x;
  }
  if (rmax > cmin) {
    cout << "-1";
    return 0;
  }
  ans = rsum * (long long)m;
  ans += csum;
  ans -= rmax * (long long)m;
  if (rmax < cmin) ans += rmax - rmax2;
  cout << ans;
  return 0;
}
