#include <bits/stdc++.h>
 
#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)
 
#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=(int)(a)-1;i>=(int)(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)
 
#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define bit(n) (1LL<<(n))
 
// #define DEBUG
 
#ifdef DEBUG
    #define dump(...) fprintf(stderr, __VA_ARGS__)
#else
    #define dump(...)
#endif
 
template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}
 
using namespace std;
using ll=long long;
using vi=vector<int>;
using vll=vector<ll>;
 
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int inf = INT_MAX;
const ll INF = LLONG_MAX;
const ll MOD = 1000000007LL;
const int dx[4]={1,0,-1,0};
const int dy[4]={0,1,0,-1};
 
ll extgcd(ll a,ll b,ll& x,ll& y){x=1,y=0;ll g=a;if(b!=0) g=extgcd(b,a%b,y,x),y-=a/b*x;return g;}
ll ADD(const ll &a, const ll &b, const ll mod=MOD) { return (a+b)%mod;}
ll SUB(const ll &a, const ll &b, const ll mod=MOD) { return (a-b+mod)%mod;}
ll MUL(const ll &a, const ll &b, const ll mod=MOD) { return (1LL*a*b)%mod;}
ll DIV(const ll &a, const ll &b, const ll mod=MOD) {ll x,y; extgcd(b,mod,x,y);return MUL(a,(x+mod)%mod,mod);}
 
int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);

    int R; cin >> R;

    string res = "AGC";
    if(R < 1200){
        res = "ABC";
    }
    else if(R < 2800){
        res = "ARC";
    }

    cout << res << endl;

    return 0;
}


#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define endl "\n"
#define REP(i,a,b) for(ll i=a;i<b;i++)
#define PER(i,b,a) for(ll i=b;i>a;i--)
#define forit(it,x) for(auto it=(x).begin();it!=(x).end();++it)
#define ull unsigned long long int
#define ld long double
#define prec(n) fixed<<setprecision(n)
#define test ll t; cin>>t; while(t--)
#define re return 0
#define pb push_back
#define PI 3.1415926535897932384626
#define MOD (ll)1000000007
#define fi first
#define se second
#define eb emplace_back
#define vll vector<ll>
#define vi  vector<int>
#define mpll map<ll,ll>
#define pll pair<ll,ll>
#define mp(x,y) make_pair(x,y)
const ll MAXI = (ll)1e9+7;
int main(){
    IOS;
//    test{
        int a;
        cin>>a;
/*        int a[n];
        REP(i,n){
           cin>>a[i];
        }
        */
        cout<<a*(1+a+a*a)<<"\n";
//    }
re;
}
