#include "stdafx.h"
#include
int _tmain(int argc, _TCHAR* argv[])
{
int grade;
scanf_s("%d", &grade);
if ( (90 <= grade) AND (grade <= 100))
printf("A");
else if (80 <= grade && grade < 90)
printf("B");
else if (70 <= grade && grade< 80)
printf("C");
else if (60 <= grade && grade < 70)
printf("D");
else
printf("不及格");
system("pause");
return 0;
}