#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse2")
using namespace std;
const long long hell = 1000000007;
long long power(long long a, long long b) {
  if (b == 0) return 1;
  if (b == 1) return a;
  long long t = power(a, b / 2);
  t %= hell;
  t *= t;
  t %= hell;
  if (b % 2)
    return (t * a) % hell;
  else
    return t;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b - a % b, a % b);
}
long long digitsum(long long x) {
  while (x > 9) {
    long long ans = 0;
    while (x != 0) {
      ans += x % 10;
      x /= 10;
    }
    x = ans;
  }
  return x;
}
long long pw(long long a, long long b) {
  long long x = a;
  for (long long i = 1; i < b; i++) {
    a = a * x;
  }
  return a;
}
bool cmp(pair<long long, long long> a, pair<long long, long long> b) {
  return a.second < b.second;
}
long long solve() {
  long long n, m;
  cin >> n >> m;
  vector<long long> a(n), b(m);
  long long mn = hell, mx = 0;
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
    mx = max(mx, a[i]);
  }
  for (long long i = 0; i < m; i++) {
    cin >> b[i];
    mn = min(mn, b[i]);
  }
  if (mn < mx) {
    cout << -1;
    return 0;
  }
  sort((a).begin(), (a).end());
  sort((b).begin(), (b).end());
  long long sum = 0;
  for (long long i = 0; i < m; i++) {
    sum += b[i];
  }
  for (long long i = 0; i < n - 1; i++) sum += a[i] * m;
  if (a[n - 1] != b[0]) {
    sum += a[n - 1];
    sum -= a[n - 2];
  }
  cout << sum;
  return 0;
}
signed main() {
  long long t = 1;
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin.exceptions(cin.failbit);
  clock_t time_req;
  time_req = clock();
  long long k = 1;
  while (t--) {
    solve();
  }
  time_req = clock() - time_req;
  return 0;
}
