#include<stdio.h>
#include<string.h>
#include<iostream>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<ctype.h>
#include<stack>
#include<math.h>
#include <string>
#include<algorithm>
#include<iomanip>
#define _for(i,a,b) for(int i = (a);i < (b);i++)
#define mset(x) memset(x,0,sizeof(x));
using namespace std;

int main() {
	long long int n,ans;
	cin>>n;
	ans = n * n *n;
	cout<<ans<<endl;
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;
typedef pair<ll, ll> Pll;
#define rep(i,n) for(int (i) = 0; (i) < (int)(n); (i)++)
#define debug(var)  do{std::cout << #var << " : ";view(var);}while(0)
template<typename T> void view(T e){std::cout << e << std::endl;}
template<typename T> void view(const std::vector<T>& v){for(const auto& e : v){ std::cout << e << " "; } std::cout << std::endl;}
template<typename T> void view(const std::vector<std::vector<T> >& vv){ for(const auto& v : vv){ view(v); } }
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
void Yes(){cout << "Yes" << endl;}
void No(){cout << "No" << endl;}
void YES(){cout << "YES" << endl;}
void NO(){cout << "NO" << endl;}
void err() {cout << -1 << endl;}
#define all(x) (x.begin(), x.end())

const int MOD = 1000000007;
const int INF = 1e9;

#define PI acos(-1);
int dx[4] = {1,-1,0,0};
int dy[4] = {0,0,1,-1};
int ddx[8] = {1,1,1,-1,-1,-1,0,0};
int ddy[8] = {0,1,-1,0,1,-1,1,-1};


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