#include<stdio.h>
#define M 1000   
int v[M],y[M];   
int main()   
{unsigned i,ok,n,nr,nr1;   
 int aux,k;   
  
FILE *f=fopen("trapez.in","r");   
FILE *g=fopen("trapez.out","w");   
  
fscanf(f,"%d",&n);   
  
for(i=1;i<=n;i++)   
 {fscanf(f,"%d",&v[i]);
  fscanf(f,"%d",&y[i]);}   
  
  
do  
{ok=0;   
 for(i=1;i<=n-1;i++)   
  if (y[i]>y[i+1]) {aux=y[i];   
            y[i]=y[i+1];   
            y[i+1]=aux;   
            ok=1;}   
 }   
while(ok);   
  
k=0;   
nr=1;   
  
for(i=1;i<=n-1;i++)   
 if (y[i]==y[i+1]) nr++;   
  
 nr1=1;   
  
 do  
 {ok=0;   
  for(i=1;i<=n-1;i++)   
   if(v[i]>v[i+1]) {aux=v[i];   
            v[i]=v[i+1];   
            v[i+1]=aux;   
            ok=1;}   
  }   
 while(ok);   
  
for(i=1;i<=n-1;i++)   
  if(v[i]==v[i+1]) nr1++;   
  
  
 if((nr1>=3)&&(nr>=3)) k+=2;   
 else k++;   
  
 fprintf(g,"%d",k);   
  
fclose(f);   
fclose(g);   
return 0;   
}