#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;

const int N = 1e5 + 5;

struct edge{
    int to, next, w;
}e[N << 1];
int head[N], cnt;
void add(int u, int v, int w){
    e[cnt] = {v, head[u], w};
    head[u] = cnt++;
}

void init(){
    memset(head, -1, sizeof(head));
    cnt = 0;
}

int hp[N];
int ans = 1e4;

int n, m, s;

void dfs(int u, int exp, int time){
    if(u == n) ans = min(ans, time);
    if(time >= ans) return;
    for(int i = head[u]; ~i; i = e[i].next){
        int v = e[i].to;
        int w = e[i].w;
        if(w > exp) continue;
        dfs(v, exp - w + hp[v], time + 1);
    }
}

void solve(){
    init();
    cin >> n >> m >> s;
    for(int i = 1; i <= n; i++) cin >> hp[i];
    for(int i = 1; i <= m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        add(u, v, w);
    }
    dfs(1, s, 0);
    cout << (ans == 1e4 ? -1 : ans) << '\n';
}

int main(){
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}