#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3c3c3c3c;
const long long LINF = 1ll * INF * INF * 2;
const int N = 1000001;
int n, m;
int a[N];
int b[N];
int main(void) {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%d", a + i);
  for (int i = 0; i < m; i++) scanf("%d", b + i);
  sort(a, a + n);
  sort(b, b + m);
  if (b[0] < a[n - 1]) {
    printf("-1");
    return 0;
  }
  long long sum = 0, sum2 = 0;
  for (int i = 0; i < n; i++) sum += a[i];
  for (int i = 0; i < m; i++) sum2 += b[i] - a[n - 1];
  if (b[0] > a[n - 1]) sum2 += a[n - 1] - a[n - 2];
  cout << sum * m + sum2;
}
