# include <cstdio>

# include <cstring>

# include <cstdlib>

# include <iostream>

# include <vector>

# include <queue>

# include <stack>

# include <map>

# include <set>

# include <cmath>

# include <algorithm>

using namespace std;

# define lowbit(x) ((x)&(-x))

# define pi acos(-1.0)

# define eps 1e-

# define MOD

# define INF

# define mem(a,b) memset(a,b,sizeof(a))

# define FOR(i,a,n) for(int i=a; i<=n; ++i)

# define FO(i,a,n) for(int i=a; i<n; ++i)

# define bug puts("H");

# define lch p<<,l,mid

# define rch p<<|,mid+,r

# define mp make_pair

# define pb push_back

# define set pabs

typedef pair<int,int> PII;

typedef vector<int> VI;

# pragma comment(linker, "/STACK:1024000000,1024000000")

typedef long long LL;

int Scan() {

    int res=, flag=;

    char ch;

    if((ch=getchar())=='-') flag=;

    else if(ch>=''&&ch<='') res=ch-'';

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

    return flag?-res:res;

}

void Out(int a) {

    if(a<) {putchar('-'); a=-a;}

    if(a>=) Out(a/);

    putchar(a%+'');

}

const int N=;

//Code begin...

typedef struct{int u, v, w;}Node;

Node edge[];

int fa[N];

bool comp(Node a, Node b){return a.w<b.w;}

int find(int x)

{

    int s, temp;

    for (s=x; fa[s]>=; s=fa[s]) ;

    while (s!=x) temp=fa[x], fa[x]=s, x=temp;

    return s;

}

void union_set(int x, int y)

{

    int temp=fa[x]+fa[y];

    if (fa[x]>fa[y]) fa[x]=y, fa[y]=temp;

    else fa[y]=x, fa[x]=temp;

}

int gcd(int x, int y){return y?gcd(y,x%y):x;}

int main ()

{

    int n, m, u, v, mi, ma, s, t, ans[];

    double answer=INF;

    scanf("%d%d",&n,&m);

    FOR(i,,m) scanf("%d%d%d",&edge[i].u,&edge[i].v,&edge[i].w);

    scanf("%d%d",&s,&t);

    sort(edge+,edge+m+,comp);

    FOR(i,,m) {

        mem(fa,-);

        mi=edge[i].w; ma=;

        FOR(j,i,m) {

            u=edge[j].u, v=edge[j].v;

            if (find(u)!=find(v)) union_set(find(u),find(v));

            if (find(s)==find(t)) {ma=edge[j].w; break;}

        }

        if (ma) if (answer>(double)ma/mi) answer=(double)ma/mi, ans[]=ma/gcd(ma,mi), ans[]=mi/gcd(ma,mi);

    }

    if (fabs(answer-INF)<eps) puts("IMPOSSIBLE");

    else {

        if (ans[]==) printf("%d\n",ans[]);

        else printf("%d/%d\n",ans[],ans[]);

    }

    return ;

}