#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>
#define nmax 250005
using namespace std;
class instream {
    public:
        instream() {}
        instream(const char *file_name) {
            input_file=fopen(file_name,"r");
            cursor=0;
            fread(buffer,SIZE,1,input_file);
        }
        inline instream &operator >>(int &n) {
            while((buffer[cursor]<'0'||buffer[cursor]>'9')&&buffer[cursor]!='-') {
                advance();
            }
            int semn=1;
            if (buffer[cursor]=='-')
                semn=-1,advance();
            n=0;
            while('0'<=buffer[cursor]&&buffer[cursor]<='9') {
                n=n*10+buffer[cursor]-'0';
                advance();
            }
            n*=semn;
            return *this;
        }
    private:
        FILE *input_file;
        static const int SIZE=1<<15;
        int cursor;
        char buffer[SIZE];
        inline void advance() {
            ++ cursor;
            if(cursor==SIZE) {
                cursor=0;
                fread(buffer,SIZE,1,input_file);
            }
        }
};
instream f("pscnv.in");
ofstream g("pscnv.out");
struct muchie{int a;int b;int c;} v[nmax*2];
int n,m,k,x,y,t[nmax];

int sortcomp(const muchie &x,const muchie &y)
{
    return x.c<y.c;
}
int tata(int x)
{
    int y=x,z;
    while (t[x]>0)
        x=t[x];
    while (t[y]>0) {
        z=t[x];
        t[y]=x;
        y=z;
    }
    return x;
}



int main()
{
    int i,j,l,p;
    f>>n>>m>>x>>y;
    if (x==y) {
        g<<1<<'\n';
        return 0;
    }
    for (i=1;i<=m;i++)
        f>>v[i].a>>v[i].b>>v[i].c;
    sort(v+1,v+m+1,sortcomp);
    for (i=1;i<=n;i++)
        t[i]=-1;
    for (i=1;i<=m;i++) {
        if (tata(v[i].a)!=tata(v[i].b))
            t[v[i].a]=v[i].b;
        if (tata(x)==tata(y)) {
            g<<v[i].c<<'\n';
            return 0;
        }
    }
    return 0;
}