1032

#include<iostream>
#include<string>
#include<map>
using namespace std;
#define N 100010
typedef struct node
{
	string data;
	int nextad;
	bool flag;
}Node;
map<int, Node> S;
Node NS[100010];
class Word
{
public:
	int firstad;
	string word;
	int l;
};
int Find(Word &W);
int main()
{
	Word A, B;
	int n;
	cin >> A.firstad >> B.firstad >> n;
	/*for (int i = 0; i < n; i++)
	{	
		int ad, nextad;
		string d;
		cin >> ad >> d >> nextad;
		S[ad] = { d,nextad,false };
	}*/
	for (int i = 0; i < n; i++)
	{
		int ad, nextad;
		string d;
		cin >> ad >> d >> nextad;
		NS[ad] = { d,nextad,false };
	}
	Find(A);
	int ans = Find(B);
	if (ans == -1)
		cout << -1 << endl;
	else
		printf("%05d\n", ans);
	//cout << A.word << endl << B.word << endl;
	system("pause");
	return 0;
}

int Find(Word &W)
{
	int addr;
	addr = W.firstad;
	while (addr != -1)
	{
		if (NS[addr].flag)
			return addr;
		else
			NS[addr].flag = true;
		addr = NS[addr].nextad;
	}
	return -1;
}