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

int main() {
    long long n; cin >> n;
    if ((n % 10) % 3 == 0) {
        cout << 1;
    } else {
        cout << 0;
    }
    return 0;
}

 $\\$

Toán tử 3 ngôi (Ternary Operator)$\\$

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

int main() {
    long long n; cin >> n;
    cout << ((n % 10) % 3 == 0 ? 1 : 0);
    return 0;
}