#include <bits/stdc++.h>
using namespace std;
int n, m, mx, mn = 0x3f3f3f3f, a[100005], b[100005], z1, z2;
bool cmp(int x, int y) { return x > y; }
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 + 1 + n, cmp);
  sort(b + 1, b + 1 + m);
  if (a[1] > b[1]) {
    puts("-1");
    return 0;
  }
  long long ans = 0;
  for (int i = 1; i <= n; ++i) ans += 1ll * a[i] * m;
  for (int i = 1; i < m; ++i) ans += b[i] - a[1];
  if (b[1] == a[1])
    ans += b[m] - a[1];
  else
    ans += b[m] - a[2];
  printf("%lld", ans);
  return 0;
}
