#include <bits/stdc++.h>
using namespace std;
const int N = 100100;
int n, m;
int b[N], g[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);
  sort(b + 1, b + 1 + n);
  sort(g + 1, g + 1 + m);
  if (b[n] > g[1]) {
    puts("-1");
    return 0;
  }
  long long ans = 0;
  for (int i = 1; i <= n; ++i) ans += (long long)m * b[i];
  for (int i = 1; i <= m; ++i) ans += g[i] - b[n];
  if (b[n] != g[1]) ans += b[n] - b[n - 1];
  printf("%lld\n", ans);
}
