Problem G: 零起點學算法27——等級分制度

#include<stdio.h>
int main()
{
    int a,b;
    while(scanf("%d %d",&a,&b)!=EOF)
    if(1500+a*5+b*5>=1800)
    printf("A");
    if(1500+a*5+b*5>=1700&&1500+a*5+b*5<=1799)
    printf("B");
    if(1500+a*5+b*5>=1600&&1500+a*5+b*5<=1699)
    printf("C");
    if(1500+a*5+b*5<1600)
    printf("D");
    return 0;
}