#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  int n, sumA = 0, sumG = 0;
  cin >> n;
  vector<pair<int, int>> vec(n);
  for (int i = 0; i < n; i++) cin >> vec[i].first >> vec[i].second;
  if (vec[0].first > vec[0].second) {
    sumG = vec[0].second;
    s.push_back('G');
  } else {
    sumA = vec[0].first;
    s.push_back('A');
  }
  for (int i = 1; i < n; i++) {
    if (sumA + vec[i].first - sumG <= 500) {
      sumA += vec[i].first;
      s.push_back('A');
    } else {
      sumG += vec[i].second;
      s.push_back('G');
    }
  }
  if (abs(sumA - sumG) <= 500)
    cout << s;
  else
    cout << -1;
  return 0;
}
