#include <bits/stdc++.h>
using namespace std;
const int INT_INF = 1e9;
const long long LL_INF = 2e18;
int n, m;
long long b[500002];
long long g[500002];
long long ans = 0;
int main() {
  scanf("%d %d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%lld", b + i);
  for (int i = 0; i < m; i++) scanf("%lld", g + i);
  sort(b, b + n);
  sort(g, g + m);
  if (g[0] < b[n - 1]) {
    printf("-1");
    return 0;
  }
  for (int i = 0; i < n; i++) ans += b[i] * m;
  for (int i = m - 1; i >= 1; i--) {
    ans += g[i] - b[n - 1];
  }
  if (g[0] != b[n - 1]) ans += g[0] - b[n - 2];
  printf("%lld", ans);
  return 0;
}
