void setup() {
  Serial.begin(9600);
float ves = 80;
float rost = 1.81;
float index = ves / (rost * rost);
if (index <= 18){
  Serial.println("недостаток");
}else if(index <= 25){
  Serial.println("норма");
}else if (index <= 30){
  Serial.println("избыток");
}else{
  Serial.println("не годен");
}



}

void loop() {
  // put your main code here, to run repeatedly:

}