HDU-2004 日期转换

#include<stdio.h>
int main()
{
    double n;
    while(scanf("%lf",&n)!=EOF)
    {
                                if(n>=0&&n<=59)
                                printf("E\n");
                                else if(n>=90&&n<=100)
                                printf("A\n");
                                else if(n>=80&&n<=89)
                                printf("B\n");
                                else if(n>=70&&n<=79)
                                printf("C\n");
                                else if(n>=60&&n<=69)
                                printf("D\n");
                                else
                                printf("Score is error!\n");
                                }
                                return 0;
                                }