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