#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
long long n, m;
long long a[maxn], b[maxn];
bool cmp(long long a, long long b) { return a > b; }
int main() {
  scanf("%lld %lld", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%lld", &a[i]);
  for (int i = 1; i <= m; i++) scanf("%lld", &b[i]);
  sort(a + 1, a + n + 1, cmp);
  sort(b + 1, b + m + 1, cmp);
  if (a[1] > b[m]) {
    cout << -1 << endl;
    return 0;
  }
  long long ans = a[1], t = m - 1, bj = 1;
  for (int i = 1; i <= m; i++) {
    if (b[i] == a[1]) continue;
    if (t == 0) {
      bj++;
      ans += a[bj];
      t = m - 1;
    }
    ans += b[i];
    t--;
  }
  for (int i = n; i > bj; i--) ans += (a[i] * m);
  ans += t * a[bj];
  cout << ans << endl;
  return 0;
}
