/*
 * ?n???????????????????????????????
????????????????????????????????????????????
????????O(n)????

????
?????????n?????n????
????????i?j???i??j???0?i,j<n?
???????0 0????????

????
????????????????????????NOT FOUND?
 *
 */

int main()
{
	int n,i,j,k,number,ju=0;
	int a[100000],b[100000],num[100000];
	cin>>n;
	i=0;
	do{
		cin>>a[i]>>b[i];
		i++;
	}
	while(a[i-1]!=0||b[i-1]!=0);
	number=i-1;
	for(k=0;k<n;k++){
		num[k]=0;
		for(j=0;j<number;j++){
			if(b[j]==k)
				num[k]++;
		}
	}
	for(i=0;i<n;i++){
		if(num[i]==n-1){
			cout<<i<<endl;
			ju++;
		}
	}
	if(ju==0)
		cout<<"NOT FOUND"<<endl;
	return 0;
}

