#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
const int mod = 1e9 + 7;
long long b[maxn], g[maxn];
int n, m;
int main() {
  scanf("%d%d", &n, &m);
  long long sum = 0, ans = 0;
  for (int i = 1; i <= n; i++) {
    scanf("%lld", &b[i]);
    sum += b[i];
  }
  sort(b + 1, b + n + 1);
  for (int i = 1; i <= m; i++) {
    scanf("%lld", &g[i]);
  }
  int flag = 0;
  for (int i = 1; i <= m; i++) {
    if (g[i] < b[n]) {
      ans = -1;
      break;
    }
    if (g[i] == b[n]) {
      ans += sum;
      flag = 2;
    }
  }
  if (ans != -1) {
    for (int i = 1; i <= m; i++) {
      if (g[i] < b[n]) {
        ans = -1;
        break;
      }
      if (g[i] != b[n]) {
        if (flag == 0) {
          ans += sum + g[i] - b[n - 1];
          flag = 1;
        } else {
          ans += sum + g[i] - b[n];
          flag = 2;
        }
      }
    }
  }
  printf("%lld\n", ans);
  return 0;
}
