#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
vector<int> adj[N], tree[N];
int from[N], to[N], h[N];
vector<int> cycle, yal;
bool nb = 0;
pair<int, int> Par[N];
long long ans[N], c[N];
void dfs(int v, int par = -1) {
  for (auto i : adj[v]) {
    int u = from[i] + to[i] - v;
    if (u == par) continue;
    if (h[u] == 0) {
      h[u] = h[v] + 1;
      Par[u] = {v, i};
      tree[v].push_back(i);
      tree[u].push_back(i);
      dfs(u, v);
    } else {
      if (abs(h[v] - h[u]) % 2 == 0) {
        if (!nb) {
          int t = u, tp = v;
          if (h[v] > h[u]) t = v, tp = u;
          while (t != tp)
            cycle.push_back(t), yal.push_back(Par[t].second), t = Par[t].first;
          cycle.push_back(tp);
          yal.push_back(i);
        }
        nb = true;
      }
    }
  }
  return;
}
long long solve(int v, int par = -1) {
  long long res = 0;
  for (auto i : tree[v]) {
    int u = from[i] + to[i] - v;
    if (u == par) continue;
    long long x = solve(u, v);
    ans[i] = c[u] - x;
    res += ans[i];
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> c[i];
  for (int i = 0; i < m; i++) {
    cin >> from[i] >> to[i];
    adj[from[i]].push_back(i);
    adj[to[i]].push_back(i);
  }
  h[1] = 1;
  dfs(1);
  if (!nb) {
    long long sum[2];
    sum[0] = sum[1] = 0;
    for (int i = 1; i <= n; i++) sum[h[i] % 2] += c[i];
    if (sum[0] != sum[1]) return cout << "NO\n", 0;
    solve(1);
    cout << "YES\n";
    for (int i = 0; i < m; i++) cout << ans[i] << '\n';
    return 0;
  }
  long long r = cycle[0];
  long long t = solve(r);
  t = (c[r] - t) / 2;
  for (int i = 0; i < (int)cycle.size(); i++)
    if (i % 2 == 0)
      ans[yal[i]] += t;
    else
      ans[yal[i]] -= t;
  cout << "YES\n";
  for (int i = 0; i < m; i++) cout << ans[i] << '\n';
  return 0;
}
