C++ :

#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;

const int maxn(5005);
const int maxe(100010);
const int inf(100000000);
struct Edge{
    int v, w, next;
}e[maxe*2];
int head[maxn], cnt;
int n, m;
int s, t, k;

void init(){
    memset(head, -1, sizeof head);
    cnt = 0;
}
void add_Edge(int u, int v, int w){
    e[cnt].v = v, e[cnt].w = w, e[cnt].next = head[u];
    head[u] = cnt ++;
}
struct Point{
    int u, w, c;
    Point(int x, int y, int z) : u(x), w(y), c(z){}
    //friend bool operator < (const Point &a, const Point &b){
    //    return a.w > b.w;
    //}
};
int dist[maxn][55];
int vis[maxn][55];

void spfa(){
    queue < Point > q;
    memset(vis, 0, sizeof vis);
    for(int i = 0; i <= n; i ++)
      for(int j = 0; j <= 60; j ++)
        dist[i][j] = inf;
    vis[s][0] = 1;
    dist[s][0] = 0;
    q.push(Point(s, 0, 0));
    while(!q.empty()){
        Point tmp = q.front(); q.pop();
        int u = tmp.u;
        int w = tmp.w;
        int c = tmp.c;
        vis[u][c] = 0;
        int cc = c;
        for(int i = head[u]; i + 1; i = e[i].next){
            int v = e[i].v;
            int cost = dist[u][cc] + e[i].w;
            if(cc + 1 > k )
              c = k;
            else
              c = cc + 1;
            if(dist[v][c] > cost){
                dist[v][c] = cost;
                if(!vis[v][c]){
                    vis[v][c] = 1;
                    q.push(Point(v, dist[v][c], c));
                }
            }
        }
    }
    if(dist[t][k] == inf) puts("-1");
    else
      printf("%d\n", dist[t][k]);
}
void input(){
    init();
    for(int i = 0; i < m; i ++){
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        add_Edge(u, v, w);
        add_Edge(v, u, w);
    }
    scanf("%d%d%d", &s, &t, &k);
    k = k/10 + (k%10 != 0);
}
int main(){
	//freopen("shortest.in","r",stdin);
	//freopen("shortest.out","w",stdout);
    while(~scanf("%d%d", &n, &m)){
        input();
        spfa();
    }
    return 0;
}

//
//#include <iostream>
//#include <cstdio>
//#include <cstring>
//#include <algorithm>
//#include <cstdlib>
//#include <ctime>
//
//typedef unsigned long long u64;
//u64 random(u64 n)
//{
//	u64 t;
//	if(n<=RAND_MAX)
//	{
//		t = rand();
//		return t%n;
//	}
//	else
//	{
//		return rand()+random(n/(RAND_MAX+1))*(RAND_MAX+1);
//	}
//}
//
//int main()
//{
//	freopen("shortest.in","w",stdout);
//	srand(time(NULL));
//	printf("4 4\n1 2 1\n2 3 2\n1 3 100\n3 4 1\n1 3 50\n");
//	for(int i = 0;i < 50; i++)
//	{
//		int N = rand()%35+1;
//		int M = rand()%85+1;
//		printf("%d %d\n",N,M);
//		for(int j = 0 ;j < M;j++)
//		{
//			int A = rand()%35+1;
//			int B = rand()%35+1;
//			int C = rand()%85+1;
//			printf("%d %d %d\n",A,B,C);
//		}
//		int S = rand()%85+1;
//		int T = rand()%35+1;
//		int K = rand()%35+1;
//		printf("%d %d %d\n",S,T,K);
//	}
//	return 0;
//}