int ledA=1;
int ledB=2;
int ledC=3;
int ledD=4;
int ledE=5;
int ledF=6;
int ledG=7;
int ledH=8;
int ledI=9;
int ledJ=10;

void setup() {
  // put your setup code here, to run once:
 pinMode(ledA, OUTPUT);
 pinMode(ledB, OUTPUT);
 pinMode(ledC, OUTPUT);
 pinMode(ledD, OUTPUT);
 pinMode(ledE, OUTPUT);
 pinMode(ledF, OUTPUT);
 pinMode(ledG, OUTPUT);
 pinMode(ledH, OUTPUT);
 pinMode(ledI, OUTPUT);
 pinMode(ledJ, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
 digitalWrite(ledA, HIGH);
 delay(1000);
 digitalWrite(ledA, LOW);
 digitalWrite(ledB, HIGH);
 delay(1000);
 digitalWrite(ledB, LOW);
 digitalWrite(ledC, HIGH);
 delay(1000);
 digitalWrite(ledC, LOW);
 digitalWrite(ledD, HIGH);
 delay(1000);
 digitalWrite(ledD, LOW);
 digitalWrite(ledE, HIGH);
 delay(1000);
 digitalWrite(ledE, LOW);
 digitalWrite(ledF, HIGH);
 delay(1000);
 digitalWrite(ledF, LOW);
 digitalWrite(ledG, HIGH);
 delay(1000);
 digitalWrite(ledG, LOW);
 digitalWrite(ledH, HIGH);
 delay(1000);
 digitalWrite(ledH, LOW);
 digitalWrite(ledI, HIGH);
 delay(1000);
 digitalWrite(ledI, LOW);
 digitalWrite(ledJ, HIGH);
 delay(1000);
 digitalWrite(ledJ, LOW);
 delay(1000);
}