#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n, m;
  cin >> n >> m;
  long long int a[n], b[m];
  long long int sum1 = 0;
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (long long int i = 0; i < m; i++) {
    cin >> b[i];
    sum1 += b[i];
  }
  sort(a, a + n);
  sort(b, b + m);
  if (a[n - 1] > b[0]) {
    cout << -1;
  } else {
    long long int j = 0;
    long long int sum2 = 0;
    if (b[0] == a[n - 1]) j++;
    sum2 += sum1;
    if (j == 0) {
      sum2 = sum2 - b[0] + a[n - 1];
      sum2 += (m - 1) * a[n - 2] + b[0];
    } else {
      sum2 += m * a[n - 2];
    }
    long long int k = n - 3;
    while (k >= 0) {
      sum2 += m * a[k];
      k--;
    }
    cout << sum2;
  }
}
