int a = 8; 
int b = 9;
int c = 11;
int d = 5;
int e = 4;
int f = 7;
int g = 6;
int h = 10;
int keyPin = 12;

// Цифра "Один"
void display1(void) { 
    digitalWrite(b,HIGH);
    digitalWrite(c,HIGH);
   } 
// Цифра "Два"
void display2(void) {
    digitalWrite(a,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(g,HIGH);
    digitalWrite(e,HIGH);
    digitalWrite(d,HIGH);
   } 
// Цифра "Три"
void display3(void) { 
    digitalWrite(a,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(c,HIGH);
    digitalWrite(d,HIGH);
    digitalWrite(g,HIGH);
   } 
// Цифра "Четыре"
void display4(void) { 
    digitalWrite(f,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(g,HIGH);
    digitalWrite(c,HIGH);
   } 
// Цифра "Пять"
void display5(void) { 
    digitalWrite(a,HIGH);
    digitalWrite(f,HIGH);
    digitalWrite(g,HIGH);
    digitalWrite(c,HIGH);
    digitalWrite(d,HIGH);
   } 
// Цифра "Шесть"
void display6(void) { 
    digitalWrite(a,HIGH);
    digitalWrite(f,HIGH);
    digitalWrite(g,HIGH);
    digitalWrite(c,HIGH);
    digitalWrite(d,HIGH);  
    digitalWrite(e,HIGH);  
   } 
// Цифра "Семь"
void display7(void) {   
    digitalWrite(a,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(c,HIGH);
   } 
// Цифра "Восемь"
void display8(void) { 
    digitalWrite(a,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(g,HIGH);
    digitalWrite(c,HIGH);
    digitalWrite(d,HIGH);  
    digitalWrite(e,HIGH);  
    digitalWrite(f,HIGH);  
   } 
// Цифра "Девять"
void display9(void) { 
    digitalWrite(a,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(g,HIGH);
    digitalWrite(c,HIGH);
    digitalWrite(d,HIGH);  
    digitalWrite(f,HIGH);  
   } 
// Цифра "Нуль"
void display0(void) { 
    digitalWrite(a,HIGH);
    digitalWrite(b,HIGH);
    digitalWrite(c,HIGH);
    digitalWrite(d,HIGH);  
    digitalWrite(e,HIGH);  
    digitalWrite(f,HIGH);  
   }
//Очистка дисплея 
void clearDisplay(void) { 
    digitalWrite(a,LOW);
    digitalWrite(b,LOW);
    digitalWrite(g,LOW);
    digitalWrite(c,LOW);
    digitalWrite(d,LOW);  
    digitalWrite(e,LOW);  
    digitalWrite(f,LOW);  
   } 

void setup() { 
    int i;
    for(i=4;i<=11;i++) 
        pinMode(i,OUTPUT);
    pinMode(keyPin,INPUT);
    digitalWrite(h,HIGH);
    display0();
 } 

int x = -1;  
int switchState = 0; 
int oldSwitchState = 0; 
boolean lightsOn = false;
void loop() { 
   switchState = digitalRead(keyPin); 
   if (switchState != oldSwitchState) {
      oldSwitchState = switchState;
      if (switchState == HIGH) {
        lightsOn = !lightsOn;
      }
    }
   if(lightsOn) {
      delay(100); 
      x = x + 1;
    }
   if (x == 0) {clearDisplay(); display0();}
   if (x == 1) {clearDisplay(); display1();}
   if (x == 2) {clearDisplay(); display2();}
   if (x == 3) {clearDisplay(); display3();}
   if (x == 4) {clearDisplay(); display4();}
   if (x == 5) {clearDisplay(); display5();}
   if (x == 6) {clearDisplay(); display6();}
   if (x == 7) {clearDisplay(); display7();}
   if (x == 8) {clearDisplay(); display8();}
   if (x == 9) {clearDisplay(); display9();}
   if (x > 9) {x = 0;}
 }