pat-1032

#include<cstdio>
using namespace std;

const int maxn=1e5+10;
int st1,st2;
int N;

struct {
    char date;
    int next;
    bool flag;
}node[maxn];


int main(){
    scanf("%d%d%d",&st1,&st2,&N);
    int adress,next;
    char date;
    while(N--){
        scanf("%d %c %d",&adress,&date,&next);
        node[adress]={date,next,false};
    }
    for(int i=st1;i!=-1;i=node[i].next){
        node[i].flag=true;
    }
    for(int i=st2;i!=-1;i=node[i].next){
        if(node[i].flag){
            printf("%05d",i);
            return 0;
        }
    }
    cout<<-1;
    return 0;
}