#include<stdio.h>
int main()
{
    char ch;
    scanf("%c",&ch);
    if(ch=='r'||ch=='y'||ch=='g')
    {
        printf("Invalid input");
        return 0;
    }
    else{
        if(ch==r)
        {
            printf("red");
        }
        else if(ch!=r)
        {
            printf("yellow");
        }
        else(ch!=r&&ch!=y)
        {
            printf("green");
        }
    }
}