#include <iostream> using namespace std; int a,b,c; int main() { while(1) { cin>>a>>b>>c; if(a==0&&b==0&&c==0) return 0; else if(a*c==b*b) cout<<"GP "<<c*(b/a)<<endl; else if(a+c==2*b) cout<<"AP "<<c+(b-a)<<endl; } }