void main()
{
int a[10000]={0},b[10000]={0},n,i,j,t;
scanf("%d",&n);
do 
{
scanf("%d %d",&i,&j);
if ((i+j)!=0)
{
a[j]=a[j]+1;
b[i]=b[i]+1;
}
}
while ((i+j)!=0);
//for (i=0;i<n;i++){printf("%d %d\n",a[i],b[i]);}
j=0;
for (i=0;i<n;i++) if ((a[i]==(n-1))&&(b[i]==0))
{ t=i;j=j+1;}
if (j<=0) printf("NOT FOUND\n"); else printf("%d\n",t);

//if (j==0)printf("%d\n",j);
}
