const int LED1 = 13;
const int LED2 = 12;
const int LED3 = 11;
const int flex = A0;

void setup() {
Serial.begin(9600);
pinMode(LED1, OUTPUT);
pinMode(LED2, OUTPUT);
pinMode(LED3, OUTPUT);
pinMode(flex, INPUT);
}

void loop() {
int f=analogRead(flex);
Serial.println(f);
if (f>=900) {
  digitalWrite(LED1,HIGH);
  digitalWrite(LED2,LOW);
  digitalWrite(LED3,LOW);
}
if (f>=850 && f<900) {
  digitalWrite(LED2,HIGH);
  digitalWrite(LED1,LOW);
  digitalWrite(LED3,LOW);
}
if (f<850){
  digitalWrite(LED3,HIGH);
  digitalWrite(LED2,LOW);
  digitalWrite(LED1,LOW);
}
delay(100);
}