#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
long long rem[maxn];
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  long long sum_girl = 0;
  long long max_boy = 0;
  long long min_girl = 1e9;
  long long min_ans = 0;
  long long num;
  for (int i = 0; i < n; i++) {
    scanf("%lld", &num);
    rem[i] = num;
    min_ans += (num * m);
  }
  sort(rem, rem + n);
  max_boy = rem[n - 1];
  for (int i = 0; i < m; i++) {
    scanf("%lld", &num);
    sum_girl += num;
    if (num < min_girl) min_girl = num;
  }
  if (min_girl < max_boy)
    printf("-1");
  else {
    min_ans = min_ans - (max_boy * m) + sum_girl;
    if (max_boy != min_girl) {
      min_ans = min_ans + rem[n - 1] - rem[n - 2];
    }
    printf("%lld", min_ans);
  }
  return 0;
}
