#include <bits/stdc++.h>

using namespace std;

typedef long long int LL;

#define st first
#define nd second
#define PII pair <int, int>

const int N = 80;
const LL INF = 1e18 + 9LL;

int n, m, k;
int pod[N];
LL dp[N][N][N];
vector <PII> G[N];

void update(int a, int b, LL cost){
    for(int i = 0; i <= pod[a] + pod[b]; ++i)
        for(int j = 0; j <= pod[a] + pod[b]; ++j)
            dp[0][i][j] = INF;

    for(int i = 0; i <= pod[a]; ++i)
        for(int j = 0; j <= pod[b]; ++j)
            for(int ii = 0; ii <= pod[a]; ++ii)
                for(int jj = 0; jj <= pod[b]; ++jj)
                    dp[0][i + j][ii + jj] = min(dp[0][i + j][ii + jj], dp[a][i][ii] + dp[b][j][jj]);

    for(int i = 0; i <= pod[a] + pod[b]; ++i)
        for(int j = 0; j <= pod[a] + pod[b]; ++j)
            dp[a][i][j] = min(dp[a][i][j], dp[0][i][j]);

    dp[a][0][1] = cost;
    pod[a] += pod[b];
}

void dfs(int u, int p, LL cost){
    for(int i = 0; i <= k; ++i)
        for(int j = 0; j <= m; ++j)
            dp[u][i][j] = INF;

    dp[u][0][1] = cost;
    dp[u][1][0] = 0;

    pod[u] = 1;
    for(auto v: G[u]){
        if(v.first == p)
            continue;

        dfs(v.first, u, v.second);
        update(u, v.first, cost);
    }

//     for(int i = 0; i <= pod[u]; ++i)
//         for(int j = 0; j <= pod[u]; ++j)
//             printf("%d :: %d %d :: %lld\n", u, i, j, dp[u][i][j]);
}

int main(){
    scanf("%d %d %d", &n, &m, &k);
    for(int i = 1; i < n; ++i){
        int u, v, c;
        scanf("%d %d %d", &u, &v, &c);

        G[u].push_back({v, c});
        G[v].push_back({u, c});
    }

    dfs(1, 0, INF);
    if(dp[1][k][m] == INF)
        puts("-1");
    else
        printf("%lld\n", dp[1][k][m]);
    return 0;
}