int main()
{
     int i,j,a[100000],b[100000],s,c[100000],n;
     scanf("%d",&n);
     
     
    for (i=0;i<n;i++) c[i]=0;
     
    
     
     scanf("%d %d",&a[0],&b[0]);
     for (i=1;;i++)
     {c[b[i-1]]=c[b[i-1]]+1;
         scanf("%d %d",&a[i],&b[i]);
    if (a[i]+b[i]==0)break;
    
    
    }
         s=0;
         for (j=0;j<n;j++)
        if  (c[j]==n-1)
        {printf("%d",j);
          s=1;}
          if(s==0) printf("NOT FOUND");
          
     
          }
     
         