#include <bits/stdc++.h>
using namespace std;
long long boy[100005], girl[100005];
int main() {
  int n, m, i;
  long long boy_max, girl_min;
  cin >> n >> m;
  for (i = 0; i < n; i++) cin >> boy[i];
  for (i = 0; i < m; i++) cin >> girl[i];
  sort(boy, boy + n);
  reverse(boy, boy + n);
  sort(girl, girl + m);
  boy_max = *max_element(boy, boy + n);
  girl_min = *min_element(girl, girl + m);
  if (boy_max > girl_min) {
    cout << "-1\n";
    return 0;
  }
  if (boy_max == girl_min) {
    long long ans = 0;
    for (i = 1; i < n; i++) ans += boy[i];
    ans *= m;
    for (i = 0; i < m; i++) ans += girl[i];
    cout << ans << '\n';
  } else {
    long long ans = 0;
    for (i = 0; i < n; i++) ans += boy[i];
    ans *= m;
    for (i = 1; i < m; i++) ans += (girl[i] - boy[0]);
    ans += (girl[0] - boy[1]);
    cout << ans << '\n';
  }
  return 0;
}
