#include <stdio.h>
#include <stdlib.h>

int cmp(const void *p,const void *q){return *(int*)p-*(int*)q;}

int solve(int *d,int m,int cur,int a,int (*f)(int))
{
  if (cur==m) return f(a);
  int g(int n){ int p=d[cur*2+1]; return f(n==p?p+1:n==p+1?p:n); }
  return solve(d,m,cur+1,a,g);
}

int main()
{
  int m,n,a,i,d[2000];
  while(scanf("%d%d%d",&n,&m,&a),m!=0){
    int id(int n){ return n; }
    for (i=0;i<m;i++) scanf("%d%d%d",d+i*2,d+i*2+1,&n);
    qsort(d,m,sizeof(int)*2,cmp);
    printf("%d\n",solve(d,m,0,a,id));
  }
  return 0;
}