#include <avr/io.h>        
  
  int main(void) 
  {  
    ddrb = ddrb & ~(1<<7);    
  
    while (1)
    {
      if(pinb & (1<<7))
        ddrb = ddrb & ~(1<<4);  
      else
        ddrb = ddrb | (1<<4);
    }
    
    return 0;
  }