#include<stdio.h>

#include<stdlib.h>

int main()

{

float s;

char c;

scanf("%f",&s);

switch((int)s/10)

{

容case 10:

case 9:

c="A";

break;

case 8:

c="B";

break;

case 7:

c="C";

break;

case 6:

c="D";

break;

case 5:

case 4:

case 3:

case 2:

case 1:

case 0:

c="E";

break;

default:

c="E";

break;

}

printf("%.1f:%c",s,c);

return 0;

}