题解 | #网购#

#include<stdio.h>
int main()
{ 
  double a,b,c,d;
  scanf("%lf %lf %lf %lf",&a,&b,&c,&d);
  if(b==c)
  {  
     if(b==11){
        if((a*0.7-d*50)<0)  printf("0.00");
        else printf("%.2lf",a*0.7-d*50);
     }
     if(b==12){
        if((a*0.8-d*50)<0)  printf("0.00");
        else printf("%.2lf",a*0.8-d*50);  
     }
  }
  else  printf("%.2lf",a);
    return 0;
}