#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using iii = pair<ii, int>;
#define vt vector
#define pq priority_queue
#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define __lcm(a, b) a * b / __gcd(a, b)
// #define multicase
const int MOD = 1e9 + 7;
const int INF = 2e9;
const int N = 2e5 + 5;

int x;

void solve() {
    int T = 1;
  #ifdef multicase
    cin >> T;
  #endif
    while(T--) {
        cin >> x;
        cout << (x < 1200 ? "ABC\n" : x < 2800 ? "ARC\n" : "AGC\n");
    }
}

int main() {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    solve();
    
}
#include <vector>
#include <stack>
#include <queue>
#include <list>
#include <bitset>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <numeric>
#include <iostream>
#include <iomanip>
#include <string>
#include <chrono>
#include <random>
#include <cmath>
#include <cassert>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <functional>
#include <sstream>

using namespace std;



int main(int argc, char** argv) {
    ios::sync_with_stdio(false);
    cin.tie(0);


    int r;
    cin >> r;
    if (r < 1200) {
        cout << "ABC\n";
    } else if (r < 2800) {
        cout << "ARC\n";
    } else {
        cout << "AGC\n";
    }

    return 0;
}