#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main(void)
{
  int score;
  while (1)
  {
    printf("请输入学生分数\n");
    scanf("%d", &score);
    if (score < 0 || score>100)
    {
      printf("输入错误\n");
    }
    else
    {
      if (score < 60)
      {
        printf("不及格\n");
      }
      else if (score >= 60 && score < 80)
      {
        printf("良好\n");
      }
      else
      {
        printf("优秀\n");
      }
    }
  }
  return 0;
}