#include <iostream>
#include <map>
#define sf(n,a) (n==a?a+1:n==a+1?a:n)
using namespace std;

int main()
{
  for (int n,m,a;cin>>n>>m>>a,n!=0;){
    multimap<int,int> mm;
    while(m--){
      int h,p,q;cin>>h>>p>>q;
      mm.insert(make_pair(-h,p));
    }
    for (multimap<int,int>::iterator p=mm.begin();p!=mm.end();p++)
      a=sf(a,p->second);
    cout<<a<<endl;
  }
  return 0;
}