#include <bits/stdc++.h>
#pragma GCC optimize(3, "Ofast", "inline")
using namespace std;
mt19937 rng_32(chrono::steady_clock::now().time_since_epoch().count());
const int mod = 1e9 + 7;
const int seed = 233;
const double PI = acos(-1.0);
const double eps = 1e-7;
const int inf = 0x3f3f3f3f;
const int max_n = 100005;
namespace {
inline int Add(int x, int y) { return (x += y) >= mod ? x - mod : x; }
inline int Sub(int x, int y) { return (x -= y) < 0 ? x + mod : x; }
inline int Mul(int x, int y) { return 1ll * x * y % mod; }
inline int Pow(int x, int y = mod - 2) {
  int res = 1;
  while (y) {
    if (y & 1) res = 1ll * res * x % mod;
    x = 1ll * x * x % mod;
    y >>= 1;
  }
  return res;
}
}  // namespace
int n, m;
int b[max_n], g[max_n];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%d", b + i);
  for (int i = 1; i <= m; i++) scanf("%d", g + i);
  long long ans = 0;
  sort(b + 1, b + n + 1);
  long long sum = 0;
  for (int i = 1; i <= n; i++) sum += b[i];
  bool f = false;
  for (int i = 1; i <= m; i++) {
    if (g[i] < b[n]) return printf("-1\n"), 0;
    if (g[i] == b[n]) f = true;
    ans += sum + g[i] - b[n];
  }
  if (f == false) ans += b[n] - b[n - 1];
  printf("%lld\n", ans);
  return 0;
}
