#include <algorithm>
#include <vector>
using namespace std;

#define pb push_back
#define mp make_pair
#define DIM 250005
#define sc second
#define fs first

vector <pair <int,pair <int,int> > > a;
int p[DIM],r[DIM];
int n,m,s,d;

void read ()
{
    int i,x,y,z;

    scanf ("%d%d%d%d",&n,&m,&s,&d);
    for (i=1; i<=m; ++i)
    {
        scanf ("%d%d%d",&x,&y,&z);
        a.pb (mp (z,mp (x,y)));
    }
}

void unite (int x,int y)
{
    if (r[x]<r[y])
        p[x]=y;
    else
        p[y]=x;
    if (r[x]==r[y])
        ++r[x];
}

int find (int x)
{
    if (x!=p[x])
        p[x]=find (p[x]);
    return p[x];
}

void solve ()
{
    int i;

    sort (a.begin (),a.end ());
    for (i=1; i<=n; ++i)
        p[i]=i;
    for (i=0; i<m; ++i)
    {
        if (find (a[i].sc.fs)!=find (a[i].sc.sc))
            unite (find (a[i].sc.fs),find (a[i].sc.sc));
        if (find (s)==find (d))
        {
            printf ("%d",a[i].fs);
            return ;
        }
    }
}

int main ()
{
    freopen ("pscnv.in","r",stdin);
    freopen ("pscnv.out","w",stdout);

    read ();
    solve ();

    return 0;
}