#include<bits/stdc++.h>
#define re register
using namespace std;
inline int read(){
	re int t=0;re char v=getchar();
	while(v<'0')v=getchar();
	while(v>='0')t=(t<<3)+(t<<1)+v-48,v=getchar();
	return t;
}
int n,m,S,T,A[300002],B[300002],C[300002],mn[300002];
char v[300002];
vector<int>G[300002];
inline void dfs(re int x){
	v[x]=1;
	for(auto z:G[x])if(!v[z])dfs(z);
}
int main(){
	n=read(),m=read(),S=read(),T=read(),C[0]=2e9;
	for(re int i=1;i<=m;++i)A[i]=read(),B[i]=read(),C[i]=read(),G[B[i]].push_back(A[i]);
	dfs(T);if(!v[S])return puts("IMPOSSIBLE"),0;
	for(re int i=1;i<=m;++i)if(v[B[i]]&&C[i]<C[mn[A[i]]])mn[A[i]]=i;
	int pos=S;vector<int>tmp;
	while(tmp.size()<1000000&&pos^T)tmp.push_back(C[mn[pos]]),pos=B[mn[pos]];
	if(tmp.size()>=1000000)puts("TOO LONG");
	else for(auto z:tmp)printf("%d ",z);
}