#define pulse A0
#define cap A1
#define buz A3
 
unsigned long valsum=0;
 
int val[8];
int minval=10000;
int maxval=0;
 
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(pulse,OUTPUT);
  pinMode(cap,INPUT);
  pinMode(buz,OUTPUT);
}
 
void loop() {
  // put your main code here, to run repeatedly:
  
  unsigned long minsum=0;
  unsigned long maxsum=0;
  unsigned int valsum=0;
  for(int i=0;i<8;i++){
    pinMode(cap,OUTPUT);
    digitalWrite(cap,LOW);
    delayMicroseconds(20);
    pinMode(cap,INPUT);
    ///////////////////////////////////////////////////    
    for (int j = 0; j < 21; j++) {
      digitalWrite(pulse,HIGH);
      delayMicroseconds(3);
      digitalWrite(pulse,LOW);
      delayMicroseconds(3);
    }
    ///////////////////////////////////////////////////
    val[i] = analogRead(cap);
  }
  for(int i=0;i<7;i++){
    for(int j=0;j<7-i;j++){
      if(val[j]>val[j+1]){
        int temp=val[j];
          val[j]=val[j+1];
          val[j+1]=temp;
      }
    }
  }
  valsum=val[2]+val[3]+val[4]+val[5];
  valsum/=4;
  maxval = max(valsum,maxval);
  if(maxval>valsum+2){
    digitalWrite(buz,HIGH);
  }
  else{
    digitalWrite(buz,LOW);
  }
  delay(1);
  /*
  Serial.print(valsum);
  Serial.print("  ");
  Serial.print(maxval);
  Serial.println(" ");
  */
}