#include <bits/stdc++.h>
using namespace std;
void ioe() {
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
  freopen("error.txt", "w", stderr);
}
int main() {
  long long n, m, i;
  scanf("%lld %lld", &n, &m);
  long long a[n];
  long long b[m];
  for (i = 0; i < n; i++) scanf("%lld", &a[i]);
  for (i = 0; i < m; i++) scanf("%lld", &b[i]);
  sort(a, a + n);
  long long b1[m];
  for (i = 0; i < m; i++) b1[i] = b[i];
  sort(b1, b1 + m);
  for (i = 0; i < m; i++) b[m - i - 1] = b1[i];
  if (a[n - 1] > b[m - 1])
    cout << (-1) << endl;
  else {
    long long s = 0;
    for (i = 0; i < m - 1; i++) s += b[i] - a[n - 1];
    if (b[m - 1] != a[n - 1]) s += b[m - 1] - a[n - 2];
    for (i = 0; i < n; i++) s += a[i] * m;
    cout << s << endl;
  }
  return 0;
}
