#include <stdio.h>
#include<string.h>
int main() 
{
    char colour[100];
    scanf("%s",colour);
    if(colour=='red')
    {
        printf("Stop");
    }
    else if(colour=='yellow')
        {
            printf("ready");
        }
    else if(colour=='green')
        {
          printf("Go");  
        }
    else
    {
        printf("INVALID INPUT");
    }
}