#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <map>
using namespace std;

const int big=9999;

int main(){
  ifstream cin("friday.in");
  for(int n,m;cin >> n >> m,(n!=0 or m!=0);){
    int ist,jst,exit;
    cin >> ist >> jst >> exit;
    ist--;jst--;exit--;
    vector<vector<int > > gi(n);
    vector<vector<int > > gj(n);
    for(int i=0;i<n;i++)
      gj[i].push_back(i);
    for(int i=0;i<m;i++){
      int s,d,e;
      cin >> s >> d >> e;
      s--;d--;
      gi[s].push_back(d);
      gi[d].push_back(s);
      gj[s].push_back(d);
      if(e==0) gj[d].push_back(s);
    }
    multimap<int,int> probes;
    probes.insert(make_pair(0,jst));
    vector<int> jcost(n,big);
    while(!probes.empty()){
      int cost = probes.begin()->first;
      int pos = probes.begin()->second;
      probes.erase(probes.begin());
      if(cost < jcost[pos]){
	jcost[pos]=cost;
	for(int k=0;k<gj[pos].size();k++){
	  probes.insert(make_pair(cost+1,gj[pos][k]));
	}
      }
    }
    
    bool found = false;
    for(int ambush_pos=0;ambush_pos<n;ambush_pos++){
      if(ambush_pos == exit) continue;
      probes.clear();
      probes.insert(make_pair(0,ist));
      vector<int> icost(n,big);
      while(!probes.empty()){
        int cost = probes.begin()->first;
        int pos = probes.begin()->second;
        probes.erase(probes.begin());
        if(cost < icost[pos] && (cost <=jcost[pos] || pos != ambush_pos)){
          icost[pos]=cost;
          for(int k=0;k<gi[pos].size();k++){
            probes.insert(make_pair(cost+1,gi[pos][k]));
          }
        }
      }
      if(icost[exit]==big){ found = true; break;}
    }
    cout << (!found? "ESCAPE" : "AMBUSHED") << endl;
    
  }
  
  return 0;
}