int k; void setup() {
 // put your setup code here, to run once:
 pinMode(13,OUTPUT);
 Serial.begin(9600); 
}
void loop() {
 // put your main code here, to run repeatedly:
 if(Serial.available()){ char 
c=Serial.read(); int m=c-'0'; 
if(m>=0 && m<=9){ k=m;
 } } digitalWrite(13,HIGH); 
delay(k*100); 
digitalWrite(13,LOW); 
delay(k*100);
}