#include <bits/stdc++.h>

using namespace std;

int main()
{
int n;
int m;
int s;
int t;
queue<int> q;
cin >> n >> m>> t;
int k[n];
vector<vector<int>> a;
a.resize(n);
for(int i = 0; i < n; i++)
    a[i].resize(0);
int found[n];
int sum = 0;
for(int i = 0; i < n; i++){
    cin >> k[i];
    //sum = sum + k[i];
    found[i] = -1;
}
int x;
int y;
for(int i = 0; i < m; i++)
{
    cin>> x>> y;
    x--;
    y--;
    a[x].resize(a[x].size() + 1);
    a[y].resize(a[y].size() + 1);
    a[x][a[x].size() - 1] = y;
    a[y][a[y].size() - 1] = x;
}
int w;
cin>> s>> w;
s--;
q.push(s);
found[s] = 0;
int ans = -1;
int v;
while (!q.empty() && ans == -1) {
        v = q.front();
        q.pop();
        for (int i = 0; i < a[v].size(); i++) {
        	//cout << "kek" << v << ' ' << k<< ' ' << "kek";
            if(found[a[v][i]] == -1) {
              //  cout << "kek" << v << ' ' << k<< "kek";
                found[a[v][i]] = found[v] + 1;
                q.push(i);
            }
        }
}
for(int i = 0; i < n; i++)
{
 // cout << found[i]<< " ";
}
cout << endl;
int j = 0;
int minn;
while (ans == -1)
{
    for(int i = 0; i < n; i++){
    	//cout << found[i]<< " "<<j <<  endl;
    	if(found[i] == j){
    	  //cout << "kek";
    	  sum += k[i];
    	}
    }
   // cout<< j<<" "<< sum<< " "<< w<< " "<< t<<endl;
    minn = min(sum,min( w, t));
    sum = sum - minn;
    w = w - minn;
    if(w == 0)
      ans = 0;
    if(sum == 0 && w !=0)
      ans = 1;
   // cout<< j<<" "<< sum<< " "<< w<< " "<< t<<endl<<  endl;
    j++;
}
if(ans == 0)
  cout << "NO";
else
  cout << "YES";
return 0; }