#include <bits/stdc++.h>
using namespace std;
vector<vector<pair<long long, long long> > > g;
vector<long long> color, cc;
vector<long long> ans;
vector<bool> used;
vector<long long> cycle, edges;
bool dfs(long long v, long long c) {
  color[v] = c;
  for (auto u : g[v]) {
    if (color[u.first] == c) {
      cycle.push_back(u.first);
      cycle.push_back(v);
      edges.push_back(u.second);
      return 1;
    }
    if (!color[u.first]) {
      if (dfs(u.first, 3 - c)) {
        if (cycle.size() == 1 || cycle[0] != cycle.back()) {
          cycle.push_back(v);
          edges.push_back(u.second);
        }
        return 1;
      }
    }
  }
  return 0;
}
long long dfs2(long long v) {
  used[v] = 1;
  for (auto u : g[v]) {
    if (edges.size() && u.second == edges[0]) continue;
    if (!used[u.first]) {
      ans[u.second] += dfs2(u.first);
    }
  }
  long long am = 0;
  for (auto u : g[v]) am += ans[u.second];
  return cc[v] - am;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  g.resize(n);
  ans.resize(m, 0);
  used.resize(n, 0);
  color.resize(n, 0);
  cc.resize(n, 0);
  for (long long i = 0; i < n; ++i) cin >> cc[i];
  for (long long i = 0; i < m; ++i) {
    long long u, v;
    cin >> u >> v;
    u--;
    v--;
    g[v].push_back(make_pair(u, i));
    g[u].push_back(make_pair(v, i));
  }
  bool ok = dfs(0, 1);
  if (!ok) {
    long long sum[2] = {0, 0};
    for (long long i = 0; i < n; ++i) sum[color[i] - 1] += cc[i];
    if (sum[0] != sum[1]) {
      cout << "NO\n";
    } else {
      cout << "YES\n";
      dfs2(0);
      for (long long i = 0; i < m; ++i) cout << ans[i] << '\n';
    }
  } else {
    cout << "YES\n";
    long long left = -dfs2(cycle[0]);
    for (long long i = 0; i < (long long)edges.size(); ++i) {
      if (i % 2)
        ans[edges[i]] += left / 2;
      else
        ans[edges[i]] -= left / 2;
    }
    for (long long i = 0; i < m; ++i) cout << ans[i] << '\n';
  }
}
