#include <bits/stdc++.h>
using namespace std;
int main()
{
  int x;
  int ans=0;
  cin>>x;
  ans=x*x;
  ans*=x;
  cout<<ans<<'\n';
  return 0;
}


#include<bits/stdc++.h>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define All(a) a.begin(),a.end()
#define INF 1000000007
const int MOD = 1000000007;
//accumulate(vec.begin(), vec.end(), 0)
//std::sort(v.begin(), v.end(), std::greater<Type>());
//set_intersection(x, x+7, y, y+6, back_inserter(v));
//set_union(x, x+7, y, y+6, back_inserter(v));
//set_difference(x, x+7, y, y+6, back_inserter(v));

int gcd(int x,int y){
  if(x%y==0) return y;
  else return gcd(y,x%y);
}

bool isPrime(int n){
  if(n < 2) return false;
  else if(n == 2) return true;
  else if(n%2==0) return false;

  for(int i=3;i<=sqrt(n);i++){
    if(n%i==0) return false;
  }
  return true;
}


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