//Chặt nhị phân + bfs (hoặc dfs cũng đc ._.)
//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 1005
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define iiii pair< ii , ii >
#define viiii vector< iiii >
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;
const int inf = 1e10;
const int minf = -1e10;

int n, m, s, t;
vector<ii> g[N];

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin >> n >> m >> s >> t;
    for(int i=1; i<=m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        g[u].pb(ii(v,w));
        g[v].pb(ii(u,w));
    }
}

int d[N];

bool ok(int z){
    queue<int> q;
    memset(d, -1, sizeof d);
    d[s] = 1;
    q.push(s);
    while (q.size()){
        int u = q.front();
        q.pop();
        for(auto i : g[u]){
            int v = i.fi;
            int uv = i.se;
            if (z <= uv && d[v]==-1){
                d[v] = 1;
                q.push(v);
            }
        }
    }
    return (d[t]!=-1);
}

void proc()
{
    int l = 1, r=1e9;
    int ans = -1;
    while (r-l>0){
        int mid=(l+r)/2;
        if (ok(mid)){
            ans = mid;
            l = mid+1;
        }
        else r = mid;
    }
    cout << ans;
}

signed main()
{
    readfile();
    proc();
    return 0;
}

//cây khung nhỏ nhất
//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 1005
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define iiii pair< ii , ii >
#define viiii vector< iiii >
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;
const int inf = 1e10;
const int minf = -1e10;

int n, m, s, t;
struct edges{
    int u, v, w;
};
bool cmp(edges a, edges b){
    return a.w > b.w;
}
edges a[10005];
int par[1005];

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin >> n >> m >> s >> t;
    for(int i=1; i<=m; i++){
        cin >> a[i].u >> a[i].v >> a[i].w;
    }
    for(int i=1; i<=n; i++) par[i] = i;
    sort(a+1,a+1+m,cmp);
}

int get(int u){
    return (par[u]==u ? u : par[u] = get(par[u]));
}

void join(int u, int v){
    u = get(u);
    v = get(v);
    par[u] = v;
}

void proc()
{
    int ans=-1;
    for(int i=1; i<=m; i++){
        int u = a[i].u;
        int v = a[i].v;
        int w = a[i].w;
        if (get(s)!=get(t)){
            join(u,v);
            ans = w;
        }
    }
    if (get(s)!=get(t)) cout << -1;
    else cout << ans;
}

signed main()
{
    readfile();
    proc();
    return 0;
}