#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;
}