#include<cstdio>

#include<iostream>

#include<algorithm>

#define R register int

using namespace std;

#define ull unsigned long long

#define ll long long

#define pause (for(R i=1;i<=10000000000;++i))

#define In freopen("NOIPAK++.in","r",stdin)

#define Out freopen("out.out","w",stdout)

namespace Fread {

static char B[<<],*S=B,*D=B;

#ifndef JACK

#define getchar() (S==D&&(D=(S=B)+fread(B,1,1<<15,stdin),S==D)?EOF:*S++)

#endif

inline int g() {

    R ret=,fix=; register char ch; while(!isdigit(ch=getchar())) fix=ch=='-'?-:fix;

    if(ch==EOF) return EOF; do ret=ret*+(ch^); while(isdigit(ch=getchar())); return ret*fix;

} inline bool isempty(const char& ch) {return (ch<=||ch>=);}

inline void gs(char* s) {

    register char ch; while(isempty(ch=getchar()));

    do *s++=ch; while(!isempty(ch=getchar()));

}

} using Fread::g; using Fread::gs;

namespace Luitaryi {

const int N=,M=;

int n,m,s,t,up,dn;

double anss=1E+;

int fa[N];

struct edge { int u,v,w;

    inline bool operator < (const edge& that) const{return w<that.w;}

}e[M];

inline int getf(int x) {return x==fa[x]?x:fa[x]=getf(fa[x]);}

inline void main() {

    n=g(),m=g();

    for(R i=;i<=m;++i) e[i].u=g(),e[i].v=g(),e[i].w=g();

    sort(e+,e+m+); s=g(),t=g();

    for(R i=;i<=m;++i) { R ans=;//枚举下界，最小的边

        for(R j=;j<=n;++j) fa[j]=j;

        for(R j=i;j<=m;++j) {//往上枚举，直到两点连通

            R uf=getf(e[j].u),vf=getf(e[j].v);

            fa[uf]=vf;

            if(getf(s)==getf(t)) {ans=j; break;}

        } if(i==&&ans==) return (void)printf("IMPOSSIBLE\n");

        if(ans==) break; register double tmp=1.0*e[ans].w/e[i].w;

        if(tmp<anss) anss=tmp,up=e[ans].w,dn=e[i].w;

    } R tmp=__gcd(up,dn); if(tmp==dn) printf("%d\n",up/dn);

    else printf("%d/%d\n",up/tmp,dn/tmp);

}

}

signed main() {

    Luitaryi::main();

    return ;

}