int a;
int b;
int c;
void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);
a = 10;
b = 20;
c =a+b;
Serial.println(c);
c =  b-a;
Serial.println(c);
c = a*b;
Serial.println(c);
c = b/a;
Serial.println(c);
c = b%a;
Serial.println(c);
c = ++a;
Serial.println(c);
c = a++;
Serial.println(c);
c +=a;
Serial.println(c);
}

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

}