Toughest Solution

#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define pb push_back
#define x first
#define y second
#define fastread ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define PI (atan(1)*4)
#define mp make_pair
using namespace std;

int main()
{
    fastread;
    int n, ans = 0, val;
    string s;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> s;
        val = 0;
        for (int j = 0; j < s.size(); j++)
            val += s[j] - '0';
        if (val % 3 == 0)
            ans++;
    }
    cout << ans << '\n';
    return 0;
}