#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m1 = 0, m2 = 0, mn1 = INT_MAX, mn2 = INT_MAX, s1 = 0, s2 = 0;
  cin >> n;
  vector<pair<int, int> > vt;
  long long tmp1, tmp2;
  for (int i = 0; i < n; i++) {
    cin >> tmp1 >> tmp2;
    vt.push_back(make_pair(tmp1, tmp2));
  }
  string ans = "";
  tmp1 = 0, tmp2 = 0;
  for (int i = 0; i < n; i++) {
    if (tmp2 + vt[i].second <= tmp1 + 500) {
      tmp2 += vt[i].second;
      ans += "G";
    } else {
      tmp1 += vt[i].first;
      ans += "A";
    }
  }
  if (!(abs(tmp1 - tmp2) <= 500)) {
    cout << -1;
    return 0;
  }
  cout << ans << "\n";
  return 0;
}
