#include<stdio.h>
#include<string.h>
int main()
{
    char st[50];
    scanf("%s",st);
    if(strcmp(st,"red")==0)
    {
        printf("STOP");
    }
    else if(strcmp(st,"yellow")==0)
    {
        printf("READY");
    }
    else if(strcmp(st,"green")==0)
    {
        printf("GO");
    }
    else
    {
        printf("Invalid input");
    }
    return 0;
}
}