#include <cstdio>

#include <cstring>

#include <cmath>

#include <string>

#include <iostream>

#include <algorithm>

#include <queue>

#include <set>

#include <map>

using namespace std;

typedef long long ll;

#define pii pair<int, int>

#define mkpii make_pair<int, int>

#define pdi pair<double, int>

#define mkpdi make_pair<double, int>

#define pli pair<ll, int>

#define mkpli make_pair<ll, int>

#define rep(i, n) for(int i=0; i<(n); ++i)

#define for1(i,a,n) for(int i=(a);i<=(n);++i)

#define for2(i,a,n) for(int i=(a);i<(n);++i)

#define for3(i,a,n) for(int i=(a);i>=(n);--i)

#define for4(i,a,n) for(int i=(a);i>(n);--i)

#define CC(i,a) memset(i,a,sizeof(i))

#define read(a) a=getint()

#define print(a) printf("%d", a)

#define dbg(x) cout << (#x) << " = " << (x) << endl

#define error(x) (!(x)?puts("error"):0)

#define printarr2(a, b, c) for1(_, 1, b) { for1(__, 1, c) cout << a[_][__]; cout << endl; }

#define printarr1(a, b) for1(_, 1, b) cout << a[_] << '\t'; cout << endl

inline const int getint() { int r=0, k=1; char c=getchar(); for(; c<'0'||c>'9'; c=getchar()) if(c=='-') k=-1; for(; c>='0'&&c<='9'; c=getchar()) r=r*10+c-'0'; return k*r; }

inline const int max(const int &a, const int &b) { return a>b?a:b; }

inline const int min(const int &a, const int &b) { return a<b?a:b; }



const int N=1005, M=10005;

struct dat { int x, y, w; }a[M];

inline const bool cmp(const dat &a, const dat &b) { return a.w<b.w; }

int p[N], ans1, ans2, n, m;

const int ifind(const int &x) { return x==p[x]?x:p[x]=ifind(p[x]); }

const int gcd(const int &a, const int &b) { return !b?a:gcd(b, a%b); }



int main() {

	read(n); read(m);

	for1(i, 1, m) read(a[i].x), read(a[i].y), read(a[i].w);

	int s=getint(), t=getint();

	sort(a+1, a+1+m, cmp);

	bool flag=1;

	for1(i, 1, m) {

		for1(j, 1, n) p[j]=j;

		int j=i;

		for(; j<=m; ++j) {

			int fx=ifind(a[j].x), fy=ifind(a[j].y);

			p[fx]=fy;

			if(ifind(s)==ifind(t)) {

				flag=0;

				if(a[j].w*ans2<=a[i].w*ans1) ans1=a[j].w, ans2=a[i].w;

				break;

			}

		}

		if(ifind(s)!=ifind(t)) break;

		if(a[j].w*ans2<=a[i].w*ans1) ans1=a[j].w, ans2=a[i].w;

	}

	if(flag) { puts("IMPOSSIBLE"); return 0; }

	int d=gcd(ans1, ans2);

	ans1/=d; ans2/=d;

	if(ans2==1) printf("%d\n", ans1);

	else printf("%d/%d\n", ans1, ans2);

	return 0;

}