#include <bits/stdc++.h>
using namespace std;
long long a[100003], b[100003];
bool vis[100003];
int main() {
  long long n, m;
  memset(vis, false, sizeof(vis));
  scanf("%I64d%I64d", &n, &m);
  long long ans = 0;
  bool suc = true;
  for (int i = 1; i <= n; i++) {
    scanf("%I64d", &a[i]);
    ans += a[i] * m;
  }
  for (int j = 1; j <= m; j++) {
    scanf("%I64d", &b[j]);
  }
  sort(a + 1, a + 1 + n);
  sort(b + 1, b + 1 + m);
  if (a[n] > b[1]) {
    printf("-1\n");
    return 0;
  }
  int now = m - 1, pos = n;
  for (int i = m; i >= 1; i--) {
    if (b[i] == a[pos] && !vis[pos]) {
      vis[pos] = true;
      now++;
    }
    if (!now) {
      now = m - 1;
      pos--;
    }
    ans += b[i] - a[pos];
    now--;
  }
  if (!suc)
    printf("-1\n");
  else
    cout << ans << endl;
  return 0;
}
