#include <bits/stdc++.h>   using namespace std;   long long int a[100005], ans[100005];   int main() {     long long int n, i, j;     cin >> n;     for (i = 0; i < n; i++) {       cin >> j;       a[j] += 1 * j;     }     ans[1] = a[1];     ans[2] = a[2];     ans[3] = a[1] + a[3];     for (i = 4; i < 100005; i++) {       ans[i] = max(ans[i - 2] + a[i], ans[i - 3] + a[i]);     }     cout << ans[100004];   }   