byte n;
byte i=0;
bool start=true;
float weight,height;
float bmi;
void setup() {
  Serial.begin(9600); 
}
void loop() { 
  if(start==true)
  {
    Serial.print("input your weight:");
    start=false;
  }  
  if(Serial.available())
  {
    n=Serial.read();    
    if(n>='0' && n<='9')
    {
      if(i==0)
      {
        n=n-'0';
        weight=10*weight+n;        
      }
      else if(i==1)
      {
        n=n-'0';
        height=10*height+n;                   
      }  
    }
    else if(n==0x0a)
    {
      if(i==0)
      {
        Serial.println(weight);
        Serial.print("input your height:");
      }
      else if(i==1)
        Serial.println(height);        
      i++;             
    } 
    if(i==2)
    {
      height=height/100;
      bmi=weight/(height*height);
      Serial.print("BMI=");
      Serial.println(bmi,1);  
      weight=0;
      height=0;   
      i=0; 
      start=true;    
    }
  }
}