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