Convert Km to Meter, Centimeter or Millimeter | C program

/*    Convert Km to Meter, Centimeter or Millimeter    */
#include<stdio.h>
int main()
{
 float km;
 char vi;
 float res;

 printf("K.M. : ");
 scanf("%f",&km);
 printf("Change KM in (M,s,m) : ");
 fflush(stdin);
 scanf("%c",&vi);
 if(vi=='M')
  res=km*1000;
 if(vi=='s')
  res=km*100000;
 if(vi=='m')
  res=km*1000000;
 printf("Answer : %.2f",res);
 return 0;
}

Bhuvan Arora