pat 1032

1032.c

#include <stdio.h>

int  node[100010];
char hash[100010];

int main()
{
    int start_a, start_b;
    int i, n;
    int a, b;
    char item;

    scanf("%d %d %d",&start_a,&start_b,&n);
    for(i = 0; i < n; i++) {
        scanf("%d %s %d", &a, &item, &b);
        node[a] = b;
    }

    while(start_a != -1) {
        hash[start_a] = 1;
        start_a = node[start_a];
    }

    while(start_b != -1) {
        if(hash[start_b]) {
            printf("%05d\n",start_b);
            return 0;
        }
        start_b = node[start_b];
    }

    puts("-1");
    return 0;
}