#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define ll long long
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
ll n,m;
cin>>n>>m;
if(m!=n-1){
cout<<0;
return 0;
}
map<pair<ll,ll>,ll>mp;
set<ll>s[n+5];
ll c[n+5],p[n+5];
fill(p,p+n+1,0);
for(ll i=1;i<=n;i++){
cin>>c[i];
}
vector<pair<ll,ll>>edge;
for(ll i=1;i<=m;i++){
ll u,v;
cin>>u>>v;
edge.pb({u,v});
s[u].insert(v);
s[v].insert(u);
p[u]++;
p[v]++;
}
queue<ll>q;
for(ll i=1;i<=n;i++){
if(p[i]==1){
q.push(i);
}
}
for(ll i=1;i<n;i++){
ll x=q.front();
q.pop();
if(p[x]==0){
continue;
}
ll y=*s[x].begin();
mp[{x,y}]=2*c[x];
c[y]-=c[x];
p[y]--;
p[x]--;
s[x].erase(y);
s[y].erase(x);
if(p[y]==1){
q.push(y);
}
}
if(c[q.front()]!=0){
cout<<0;
return 0;
}
for(auto [u,v]:edge){
cout<<mp[{u,v}]+mp[{v,u}]<<"\n";
}
}
