#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define f(i,j,n) for(int i=j;i<=n;i++)
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int r;
    cin>>r;
    if(r<1200)
      cout<<"ABC";
    else if(r<2800 && r>=1200)
     cout<<"ARC";
    else 
    cout<<"AGC";
} 

#include<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<cstring>
#include<vector>
#include<list>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<stack>
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define mp make_pair
#define mt make_tuple
#define pqueue priority_queue
const int inf=1e9+7;
const ll mod=1e9+7;
const ll mod1=998244353;
const ll big=1e18;
const double PI=2*asin(1);

int main() {
  int N;
  cin>>N;
  cout<<(N-2)*180<<endl;
}

