#include <stdio.h> 
  #define boyut 15 
  void sirala(int [],int); 
  int arama(int [],int,int); 
  int main() 
  { 
  	int sonuc; 
  	int ara; 
  	scanf("%d",&ara); 
  	int a[boyut]={3,15,2,1,4,5,6,7,8,9,12,11,10,14,13}; 
         int i;      
  	int b[boyut]; 
  	for(i=0;i<boyut;i++) b[i]=a[i]; 
  	sirala(b,boyut); 
      
  	sonuc=arama(b,boyut,ara); 
  	 
  	if(sonuc==-1) { printf("yok"); 
  		} 
  		else { 
  		printf("\n %d",sonuc); 
  	} 
  return 0;	 
  } 
   
   
   
   
   
   
   
   
   
   
  void sirala(int c[],int boy) 
  	{ 
            int tut,tur,a; 
  		tur=boyut; 
  		for(tur=0;tur<boyut;tur++) { 
  			for(a=0;a<boyut-1;a++) { 
  				if(c[a]>c[a+1]) { 
  					tut=c[a]; 
  					c[a]=c[a+1]; 
  					c[a+1]=tut; } } 
  		} 
  	} 
   
  	int arama(int d[],int boybaba,int aaa) { 
           
  		int orta,enust,enalt; 
                enalt=0; 
  		enust=boyut-1; 
  		orta=(enust+enalt)/2; 
  		int x=0; 
  		while(x==0) { 
                                     
  			if(aaa==d[orta]) { return orta; 
  			 
  				break;} 
  			if(aaa>d[orta]) {  
  				if(aaa==d[enust]) {return enust; 
  				 
  					break;} 
  				enalt=orta+1; 
  				orta=(enalt+enust)/2; 
  			 
  				continue; 
  			} 
  			if(aaa<d[orta]) { 
  				if(aaa==d[enalt])  {  return enalt; 
  				 
  					break;} 
  				enust=orta-1; 
  				orta=(enalt+enust)/2; 
  				continue; } 
  	 
   
  			} 
  return -1; 
  	}