#include <bits/stdc++.h>
using namespace std;
template <class X, class Y>
bool minimize(X &x, const Y &y) {
  X eps = 1e-9;
  if (x > y + eps) {
    x = y;
    return true;
  } else
    return false;
}
template <class X, class Y>
bool maximize(X &x, const Y &y) {
  X eps = 1e-9;
  if (x + eps < y) {
    x = y;
    return true;
  } else
    return false;
}
template <class T>
T Abs(const T &x) {
  return (x < 0 ? -x : x);
}
int minRow[100100], maxCol[100100], numRow, numCol;
long long process(void) {
  scanf("%d%d", &numRow, &numCol);
  for (int i = (1), _b = (numRow); i <= _b; i++) scanf("%d", &minRow[i]);
  for (int i = (1), _b = (numCol); i <= _b; i++) scanf("%d", &maxCol[i]);
  sort(minRow + 1, minRow + numRow + 1);
  sort(maxCol + 1, maxCol + numCol + 1);
  if (minRow[numRow] > maxCol[1]) return -1;
  long long sum = 0;
  for (int i = (1), _b = (numRow); i <= _b; i++)
    sum += 1LL * numCol * minRow[i];
  for (int j = (1), _b = (numCol); j <= _b; j++)
    sum += maxCol[j] - minRow[numRow];
  if (maxCol[1] > minRow[numRow]) sum += minRow[numRow] - minRow[numRow - 1];
  return sum;
}
int main(void) {
  cout << process() << endl;
  return 0;
}
