To store English words, one method is to use linked lists and store a word letter by letter. To save some space, we may let the words share the same sublist if they share the same suffix. For example, "loading" and "being" are stored as showed in Figure 1.

Figure 1

You are supposed to find the starting position of the common suffix (e.g. the position of "i" in Figure 1).

Input Specification:

Each input file contains one test case. For each case, the first line contains two addresses of nodes and a positive N (<= 10⁵), where the two addresses are the addresses of the first nodes of the two words, and N is the total
number of nodes. The address of a node is a 5-digit positive integer, and NULL is represented by -1.

Then N lines follow, each describes a node in the format:

Address Data Next

where Address is the position of the node, Data is the letter contained by this node which is an English letter chosen from {a-z, A-Z}, and Next is the position of the next node.

Output Specification:

For each case, simply output the 5-digit starting position of the common suffix. If the two words have no common suffix, output "-1" instead.

Sample Input 1:

11111 22222 9

67890 i 00002

00010 a 12345

00003 g -1

12345 D 67890

00002 n 00003

22222 B 23456

11111 L 00001

23456 e 67890

00001 o 00010

Sample Output 1:

67890

Sample Input 2:

00001 00002 4

00001 a 10001

10001 s -1

00002 a 10002

10002 t -1

Sample Output 2:

-1

#include<iostream>

#include<cstring>

using namespace std;

struct node

{

  int k;

  int next;

};

node nd[100005];

int main()

{

  int x, y, n,a,b,i,j;

  char s;

  scanf("%d%d%d",&x,&y,&n);

    memset(nd,0,sizeof(nd));

    while(n--)

    {

      scanf("%d %c %d",&a,&s,&b);

      nd[a].next=b;

    }

i=x;

while(i!=-1)

{

nd[i].k=1;

i=nd[i].next;

}

i=y;

while(i!=-1&&!nd[i].k)

{

i=nd[i].next;

}

if(i==-1)

printf("-1\n");

else

printf("%05d\n",i);

  return 0;

}