1 #include <bits/stdc++.h>
2 using namespace std;
3 #define _for(i,a,b) for(int i = (a);i < b;i ++)
4 #define _rep(i,a,b) for(int i = (a);i > b;i --)
5 #define INF 0x3f3f3f3f
6 #define pb push_back
7 #define maxn 5000039
8 typedef long long ll;
9 inline ll read()
10 {
11 ll ans = 0;
12 char ch = getchar(), last = ' ';
13 while(!isdigit(ch)) last = ch, ch = getchar();
14 while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
15 if(last == '-') ans = -ans;
16 return ans;
17 }
18 inline void write(ll x)
19 {
20 if(x < 0) x = -x, putchar('-');
21 if(x >= 10) write(x / 10);
22 putchar(x % 10 + '0');
23 }
24 int n,m,k;
25 int tot,ver[maxn],Next[maxn],head[maxn],val[maxn];
26 void add(int x,int y,int t)
27 {
28 ver[++tot] = y,Next[tot] = head[x],head[x] = tot,val[tot] = t;
29 }
30 typedef pair<int,int> P;
31 int d[maxn];
32 void shortest_path(int s)
33 {
34 priority_queue<P,vector<P>,greater<P>> que;
35 memset(d,0x3f,sizeof(d));
36 d[s] = 0;
37 que.push(P{0,s});
38
39 while(!que.empty())
40 {
41 P p = que.top();que.pop();
42 int v = p.second;
43 if(d[v] < p.first) continue;
44 for(int i = head[v]; i; i = Next[i])
45 {
46 // cout << i << endl;
47 int y = ver[i];
48 int w = val[i];
49 if(d[y] > d[v] + w)
50 {
51 d[y] = d[v] + w;
52 que.push(P{d[y],y});
53 }
54 }
55 }
56 }
57 int main()
58 {
59 n = read(), m = read(), k = read();
60 _for(i,1,m+1)
61 {
62 int u,v,t;
63 u = read();v = read();t = read();
64 add(u,v,t),add(v,u,t);
65 _for(j,1,k+1)
66 {
67 add(j*n+u,j*n+v,t),add(j*n+v,j*n+u,t);
68 add((j-1)*n+u,j*n+v,0),add((j-1)*n+v,j*n+u,0);
69 }
70 }
71 shortest_path(1);
72 int ans = d[n];
73 _for(i,1,k+1)
74 ans = min(ans,d[i*n+n]);
75 write(ans);
76 return 0;
77 }
