#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 100;
int a[N], b[N];
int main() {
  long long ans = 0;
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  for (int i = 1; i <= m; i++) scanf("%d", &b[i]);
  sort(a + 1, a + 1 + n);
  sort(b + 1, b + 1 + m);
  if (a[n] > b[1]) {
    puts("-1");
    return 0;
  }
  for (int i = 1; i <= n; i++) ans += a[i];
  ans *= m;
  for (int i = 2; i <= m; i++) ans += b[i] - a[n];
  if (b[1] != a[n]) ans += b[1] - a[n - 1];
  cout << ans << endl;
}
