Omenat

input/code.cpp: In function 'int main()':
input/code.cpp:30:10: error: expected ';' before 'mods'
   ans ++ mods[2] / 3;
          ^~~~

#include <bits/stdc++.h>
using namespace std;

const int mx = 1e5;
typedef long long ll;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  ll n;
  cin >> n;

  ll mods[3];
  mods[0]=mods[1]=mods[2] = 0;
  for (int i = 0; i < n; ++i) {
    int t;
    cin >> t;
    mods[t % 3]++;
  }

  ll ans = mods[0];
  ll mn = min(mods[1], mods[2]);
  ans += 2*mn;
  
  mods[1] -= mn;
  mods[2] -= mn;
  ans += mods[1] / 3;
  ans ++ mods[2] / 3;

  cout << ans << '\n';
}