#include <bits/stdc++.h>
using namespace std;
int n, m, a[111111], b[111111];
long long sum;
int main() {
  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 + n + 1);
  sort(b + 1, b + m + 1);
  if (a[n] > b[1]) {
    printf("-1\n");
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    sum += a[i];
  }
  sum = sum * m;
  if (a[n] != b[1]) {
    for (int i = 1; i < m; i++) {
      sum += b[i];
      sum -= a[n];
    }
    sum += b[m];
    sum -= a[n - 1];
  } else {
    for (int i = 1; i <= m; i++) {
      sum += b[i];
      sum -= a[n];
    }
  }
  printf("%lld\n", sum);
  return 0;
}
