#include <stdio.h>
int main()
{
	int x;
	scanf("%d",&x);
	if( x>=90 )
		printf("   S   \n");
	else if ( x>=80 )
		printf("   A   \n");
	else if ( x>=70 )
		printf("    B  \n");
	else
		printf("    C \n");
	return 0;
}