#include<stdio.h>

int main(void){
    
    int N;
    scanf("%d",&N);
    
    int x[40],y[40];
    for(int i=0;i<N*2;i++){
        scanf("%d%d",&x[i],&y[i]);  }
    
    
    int Ax=2,Ay=8,Bx=3,By=9,Cx=7,Cy=9;
    
    
    for(int i=0;i<N*2;i+=2){
        if(x[i]==Ax&&y[i]==Ay){Ax=x[i+1];Ay=y[i+1];}
        else if(x[i]==Bx&&y[i]==By){Bx=x[i+1];By=y[i+1];}
        else if(x[i]==Cx&&y[i]==Cy){Cx=x[i+1];Cy=y[i+1];}    }
    

  
    if(Ax==5&&Ay==8&&Bx==4&&By==8&&Cx==6&&Cy==8)
        printf("YES\n");
    else printf("NO\n");
    
    return 0;
    
}