#include<iostream>

#include<cstdio>

#include<cstring>

#include<cmath>

using namespace std;

const int inf=0x3f3f3f3f;

const double eps=1e-;

int n,L,U,x,y,v;

struct pas{int y,nxt,real_dis;}g[];int h[],tot=;

bool vis[];

int sz[],dep[],mx_sz[],S,rt;

void get_rt(int x,int f)

{

    sz[x]=;dep[x]=dep[f]+;mx_sz[x]=;

    for (int i=h[x];i;i=g[i].nxt)

    if (g[i].y!=f&&!vis[g[i].y])

    {

        get_rt(g[i].y,x),sz[x]+=sz[g[i].y];mx_sz[x]=max(mx_sz[x],sz[g[i].y]);

    }

    mx_sz[x]=max(mx_sz[x],S-sz[x]);

    if (mx_sz[x]<mx_sz[rt]) rt=x;

}

double dis[],mx[];

int fa[];

int q[],dis_q[],l,r;

bool check(int x,double d)

{

    int _sz=,u,v;

    for (int i=h[x];i;i=g[i].nxt)

    {

        fa[g[i].y]=x;

        l=,r=;q[]=g[i].y;dis[g[i].y]=g[i].real_dis-d;dep[g[i].y]=;

        while (l<=r)

        {

            u=q[l];l++;

            if (dep[u]>U) break;

            for (int t=h[u];t;t=g[t].nxt)

            if (!vis[g[t].y]&&g[t].y!=fa[u])

            {

                v=g[t].y;

                fa[v]=u;

                dis[v]=dis[u]+g[t].real_dis-d;

                dep[v]=dep[u]+;

                if (dep[v]>U) break;

                q[++r]=v;

            }

        }

        int re=r,now=_sz;l=,r=;

        for (int j=;j<=re;j++)

        {

            u=q[j];

            while (now>=&&dep[u]+now>=L)

            {

                while (l<=r&&mx[dis_q[r]]<mx[now]) r--;

                dis_q[++r]=now;now--;

            }

            while (l<=r&&dis_q[l]+dep[u]>U) l++;

            if (l<=r&&dis[u]+mx[dis_q[l]]>=) return ;

        }

        for (int t=_sz+;t<=dep[q[re]];t++) mx[t]=-inf;

        for (int t=;t<=re;t++) mx[dep[q[t]]]=max(mx[dep[q[t]]],dis[q[t]]);

        _sz=max(_sz,dep[q[re]]);

    }

    return ;

}

double lim_l=1e9,lim_r=,ans=;

void solve(int x)

{

    rt=;get_rt(x,);vis[rt]=;

    double l=lim_l>ans?lim_l:ans,r=lim_r,mid;

    while (r-l>eps)

    {

        mid=(l+r)/;

        if (check(rt,mid)) l=mid;else r=mid;

    }ans=l;

    for (int i=h[rt];i;i=g[i].nxt)

    if (!vis[g[i].y]&&sz[g[i].y]>=L)

    {

        S=sz[g[i].y];solve(g[i].y);

    }

}

int main()

{

    scanf("%d%d%d",&n,&L,&U);

    for (int i=;i<n;i++)

    {

        scanf("%d%d%d",&x,&y,&v);

        g[++tot]=pas{y,h[x],v};h[x]=tot;

        g[++tot]=pas{x,h[y],v};h[y]=tot;

        lim_l=min(lim_l,(double)v);

        lim_r=max(lim_r,(double)v);

    }

    mx_sz[]=inf;dep[]=-;

    S=n;solve();

    printf("%.3f",ans);

}