#include<cstdio>

 #include<cstring>

 #include<algorithm>

 using namespace std;

 int inline readint(){

     int Num;char ch;

     while((ch=getchar())<''||ch>'');Num=ch-'';

     while((ch=getchar())>=''&&ch<='') Num=Num*+ch-'';

     return Num;

 }

 int N,M,S,T;

 struct EDGE{

     int u,v,w;

     bool operator < (const EDGE &_)const{

         return w<_.w;

     }

 }edge[];

 int fa[];

 int inline Getfa(int x){

     return fa[x]==x?x:fa[x]=Getfa(fa[x]);

 }

 int inline Gcd(int a,int b){

     return !b?a:Gcd(b,a%b);

 }

 int main(){

     N=readint();

     M=readint();

     for(int i=;i<=M;i++){

         edge[i].u=readint();

         edge[i].v=readint();

         edge[i].w=readint();

     }

     sort(edge+,edge++M);

     S=readint();

     T=readint();

     int ansu=,ansd=;

     for(int i=;i<=M;i++){

         for(int j=;j<=N;j++) fa[j]=j;

         int mx;

         for(int j=i;j<=M;j++){

             int fx=Getfa(edge[j].u),

                 fy=Getfa(edge[j].v);

             if(fx==fy) continue;

             mx=edge[j].w;

             fa[fx]=fy;

             if(Getfa(S)==Getfa(T)) break;

         }

         if(Getfa(S)!=Getfa(T)) break;

         if(mx*ansd<ansu*edge[i].w){

             ansu=mx;

             ansd=edge[i].w;

         }

     }

     if(ansu==){

         puts("IMPOSSIBLE");

         return ;

     }

     int gcd=Gcd(ansu,ansd);

     ansu/=gcd;

     ansd/=gcd;

     if(ansd>) printf("%d/%d\n",ansu,ansd);

     else printf("%d\n",ansu);

     return ;

 }