#include <bits/stdc++.h>
using namespace std;
vector<vector<pair<long long, long long>>> graf;
vector<bool> was;
vector<long long> w;
vector<long long> res;
map<pair<long long, long long>, long long> e2i;
void Add(long long a, long long b, long long c) {
  w[a] += c;
  w[b] += c;
  res[e2i[{a, b}]] -= c;
}
void DFS(long long v) {
  if (was[v]) return;
  was[v] = true;
  for (int i = 0; i < ((long long)(graf[v]).size()); i++) {
    long long u = graf[v][i].first;
    DFS(u);
    Add(v, u, -w[u]);
  }
}
int main() {
  cin.sync_with_stdio(0);
  long long n, m;
  cin >> n >> m;
  was = vector<bool>(n, false);
  for (int i = 0; i < n; i++) {
    long long x;
    cin >> x;
    w.push_back(x);
  }
  graf = vector<vector<pair<long long, long long>>>(n);
  for (long long i = 0; i < m; i++) {
    long long a, b;
    cin >> a >> b;
    a--;
    b--;
    graf[a].push_back({b, i});
    graf[b].push_back({a, i});
    e2i[{a, b}] = i;
    e2i[{b, a}] = i;
  }
  queue<long long> q;
  q.push(0);
  vector<long long> mark(n, -1);
  mark[0] = 0;
  vector<long long> par(n, -1);
  deque<long long> cycle;
  long long sumB = 0, sumW = 0;
  while (((long long)(q).size()) > 0) {
    long long v = q.front();
    q.pop();
    for (long long i = 0; i < ((long long)(graf[v]).size()); i++) {
      long long u = graf[v][i].first;
      if (u == par[v]) continue;
      if (mark[u] != -1) {
        if (((long long)(cycle).size()) % 2 == 1) continue;
        long long a = v, b = u;
        if (mark[a] != mark[b]) {
          if (((long long)(cycle).size()) > 0) continue;
          b = par[b];
          cycle.clear();
          cycle.push_back(b);
        } else {
          cycle.clear();
        }
        while (a != b) {
          cycle.push_back(a);
          cycle.push_front(b);
          a = par[a];
          b = par[b];
        }
        cycle.push_back(a);
        break;
      } else if (mark[u] == -1) {
        mark[u] = (mark[v] + 1) % 2;
        q.push(u);
        par[u] = v;
      }
    }
    if (mark[v] == 0) {
      sumB += w[v];
    } else {
      sumW += w[v];
    }
  }
  res = vector<long long>(m, 1);
  for (long long i = 0; i < n; i++) w[i] -= ((long long)(graf[i]).size());
  if (((long long)(cycle).size()) == 0) {
    cycle.push_back(0);
    cycle.push_back(graf[0][0].first);
  }
  if (((long long)(cycle).size()) % 2 == 0) {
    if (sumB != sumW) {
      cout << "NO" << endl;
      return 0;
    }
    DFS(cycle[0]);
  } else {
    DFS(cycle[0]);
    if (w[cycle[0]] % 2 != 0) {
      cout << "NO" << endl;
      return 0;
    }
    Add(cycle[0], cycle[1], -w[cycle[0]] / 2);
    for (int i = 1; i < ((long long)(cycle).size()) - 1; i++) {
      Add(cycle[i], cycle[i + 1], -w[cycle[i]]);
    }
    Add(cycle[0], cycle.back(), -w[cycle[0]]);
  }
  cout << "YES" << endl;
  for (int i = 0; i < m; i++) {
    cout << res[i] << endl;
  }
  return 0;
}
