#include <iostream>
#include <cstdio>

using namespace std;

int main( int argc , char * argv[] ) {

    int a,b,c;

    scanf("%d%d%d" , &a,&b,&c);
    while ( a != 0 || b != 0 || c != 0 ) {

        if ( b - a == c - b ) {
            printf("AP %d\n" , c + (c-b) );
        }
        else if ( b/a == c/b ) {
            printf("GP %d\n" , c * (c/b));
        }

        scanf("%d%d%d" , &a,&b,&c);
    }

    return 0;
}