#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, m, minm = INT_MAX;
  long long int out = 0, sum2 = 0;
  cin >> n >> m;
  long long int b[n], g[m];
  for (int i = 0; i < n; i++) {
    cin >> b[i];
  }
  for (int i = 0; i < m; i++) {
    cin >> g[i];
    sum2 += g[i];
    minm = min(minm, g[i]);
  }
  sort(b, b + n);
  if (minm < b[n - 1]) {
    cout << -1;
    return 0;
  }
  out = sum2;
  for (int i = 0; i < n - 2; i++) {
    out += (m * b[i]);
  }
  if (minm == b[n - 1]) {
    out += (m * b[n - 2]);
  } else {
    out += ((m - 1) * b[n - 2]);
    out += b[n - 1];
  }
  cout << out;
  return 0;
}
