#include<bits/stdc++.h>
using namespace std;


#define li          long long int
#define rep(i,to)   for(li i=0;i<((li)(to));i++)
#define repp(i,start,to)    for(li i=(li)(start);i<((li)(to));i++)
#define pb          push_back
#define sz(v)       ((li)(v).size())
#define bgn(v)      ((v).begin())
#define eend(v)     ((v).end())
#define allof(v)    (v).begin(), (v).end()
#define dodp(v,n)       memset(v,(li)n,sizeof(v))
#define bit(n)      (1ll<<(li)(n))
#define mp(a,b)     make_pair(a,b)
#define rin rep(i,n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1


#define idp if(DBGP)
#define F first
#define S second
#define p2(a,b)     idp cout<<a<<"\t"<<b<<endl
#define p3(a,b,c)       idp cout<<a<<"\t"<<b<<"\t"<<c<<endl
#define p4(a,b,c,d)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<endl
#define p5(a,b,c,d,e)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<endl
#define p6(a,b,c,d,e,f)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<endl
#define p7(a,b,c,d,e,f,g)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<endl
#define p8(a,b,c,d,e,f,g,h)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<endl
#define p9(a,b,c,d,e,f,g,h,i)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<"\t"<<i<<endl
#define p10(a,b,c,d,e,f,g,h,i,j)        idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<"\t"<<i<<"\t"<<j<<endl
#define foreach(it,v)   for(__typeof((v).begin()) it=(v).begin(); it!=(v).end(); ++it)
#define p2p(x)      idp p2((x).F, (x).S)
#define dump(x,n)   idp{rep(i,n){cout<<x[i]<<" ";}puts("");}
#define dump2(x,n)  idp{rep(i,n){cout<<"["<<x[i].F<<" , "<<x[i].S<<"] ";}puts("");}
#define dumpi(x)    idp{foreach(it, x){cout<<(*it)<<" ";}puts("");}
#define dumpi2(x)   idp{foreach(it, x){cout<<"["<<(it)->F<<" , "<<(it)->S<<"] ";}puts("");}

#define read2d(a,w,h)   rep(i,h)rep(j,w)cin>>a[i][j]
#define dump2d(a,w,h)   rep(i,h){rep(j,w)cout<<a[i][j]<<" ";puts("");}

typedef pair<li, li> PI;


int main() {
    li n,k,m;
    cin>>n>>k>>m;
    li sum=0;
    rep(i,n-1){
        li x;
        cin>>x;
        sum+=x;
    }
    li rest = m*n-sum;
    if(rest>k){
        puts("-1");
    }else {
        cout<<max(0ll, rest)<<endl;
    }

    return 0;
}
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds; 
#define p(x,y) pair<x,y>
#define oset(x) tree<x, null_type, less<x>, rb_tree_tag, tree_order_statistics_node_update>
#define all(x) (x).begin(),(x).end()
#define ll long long
#define scan(a) for(auto &it:a)cin>>it;
#define print(a) {for(auto it:a)cout<<it<<" ";cout<<endl;}
#define out(x) cout<<((x)?"YES":"NO")<<endl;
#define rep(i, begin, end) for (__typeof(end) i = (begin) - ((begin) > (end)); i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define int ll
#define prime (int)(1e9+7)
void solve()
{
    int n;
    cin>>n;
    vector<vector<p(int,int)>> g(n+1,vector<p(int,int)>());
    rep(i,1,n)
    {
        int u,v,we;
        cin>>u>>v>>we;
        g[u].push_back({v,we});
        g[v].push_back({u,we});
    }
    vector<int> dist(n+1,-1),kbit(61,0);
    queue<int> q;
    q.push(1LL);
    dist[1]=0;
    while(!q.empty())
    {
        int p=q.front();
        q.pop();
        for(p(int,int) ch:g[p])
        {
            if(dist[ch.first]==-1)
            {
                q.push(ch.first);
                dist[ch.first]=dist[p]^ch.second;
                for(int i=0LL;i<61LL;i++)
                {
                    if(dist[ch.first]>>i&1)
                        kbit[i]++;
                }
            }
        }
    }
    int ans=0;
    for(int i=0;i<61;i++)
    {
        int t=(((1LL<<i)%prime)*(n-kbit[i]))%prime;
        t=(t*kbit[i])%prime;
        ans=(t+ans)%prime;
    }
    cout<<ans;
}
int32_t main()
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);
    int t=1;
    //init();
    //cin>>t;
    while(t--)
    {
        solve();
    }
    return 0;
}
