#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int a, b, c, d, e, f, g, h, i, j, k;
  string l;
  cin >> a >> b;
  int aa[a];
  int ab[b];
  d = 0;
  for (c = 0; c < a; ++c) {
    cin >> aa[c];
    d = d + aa[c];
  }
  for (c = 0; c < b; ++c) {
    cin >> ab[c];
  }
  sort(aa, aa + a);
  sort(ab, ab + b);
  if (aa[a - 1] > ab[0])
    cout << "-1" << endl;
  else {
    d = d * b;
    for (c = b - 1; c > 0; --c) {
      d = d + ab[c] - aa[a - 1];
    }
    if (ab[0] == aa[a - 1])
      cout << d << endl;
    else
      cout << d + ab[0] - aa[a - 2] << endl;
  }
  return 0;
}
