/**
    O(m log Val)
**/
#include<bits/stdc++.h>
#define maxN 250005
#define INF 10005
using namespace std;
int n,m,x,y,c,st,dr,mid,sol;
bool seen[maxN];
deque<int> q;
vector<pair<int,int> > v[maxN],L[maxN];
inline void RunBfs(int val)
{
    q.push_back(x);
    seen[x]=1;
    while(!q.empty())
    {
        int nod=q.front();
        q.pop_front();
        for(vector<pair<int,int> >::iterator it=v[nod].begin();it!=v[nod].end();it++)
        {
            if(seen[it->first] || it->second>val) continue;
            seen[it->first]=1;
            q.push_back(it->first);
        }
    }
}
int main()
{
    freopen("pscnv.in","r",stdin);
    freopen("pscnv.out","w",stdout);
    scanf("%d%d%d%d",&n,&m,&x,&y);
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d%d",&x,&y,&c);
        v[x].push_back({y,c});
        v[y].push_back({x,c});
    }
    for(int i=1;i<=n;i++)
    {
        sort(v[i].begin(),v[i].end());
        for(vector<pair<int,int> >::iterator it=v[i].begin();it!=v[i].end();it++)
        {
            if(it==v[i].begin() || it->first!=(it-1)->first)
            {
                L[i].push_back(*it);
            }
        }
        v[i].clear();
        for(vector<pair<int,int> >::iterator it=L[i].begin();it!=L[i].end();it++)
        {
            v[i].push_back(*it);
        }
    }
    st=0;
    dr=INF;
    while(st<=dr)
    {
        int mid=st+((dr-st)>>1);
        memset(seen,0,sizeof(seen));
        RunBfs(mid);
        if(seen[y])
        {
            sol=mid;
            dr=mid-1;
        }
            else st=mid+1;
    }
    printf("%d\n",sol);
    return 0;
}