#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
struct edge {
  int u, v;
  int adj(int x) { return u + v - x; }
};
int n, c[N];
vector<int> adj[N];
vector<edge> e;
int lvl[N], pre[N], root;
vector<int> cycle;
void dfs1(int u) {
  for (auto ind : adj[u])
    if (ind != pre[u]) {
      auto ei = e[ind];
      int v = ei.adj(u);
      if (lvl[v]) {
        if ((lvl[u] + lvl[v]) % 2 == 0 && cycle.empty()) {
          for (int w = u; w != v; w = e[pre[w]].adj(w)) cycle.push_back(pre[w]);
          reverse((cycle).begin(), (cycle).end());
          cycle.push_back(ind);
          root = v;
        }
      } else {
        lvl[v] = lvl[u] + 1;
        pre[v] = ind;
        dfs1(v);
      }
    }
}
long long int ans[N];
bool vis[N];
long long int dfs2(int u, int pre) {
  if (vis[u]) return 0;
  vis[u] = 1;
  long long int sum = 0;
  for (auto ind : adj[u])
    if (ind != pre) {
      int v = e[ind].adj(u);
      sum += dfs2(v, ind);
    }
  if (pre != -1) ans[pre] = c[u] - sum;
  return c[u] - sum;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int m;
  cin >> n >> m;
  for (int i = 0; i < (int)(n); i++) cin >> c[i];
  e.resize(m);
  for (int i = 0; i < (int)(m); i++) {
    cin >> e[i].u >> e[i].v;
    e[i].u--;
    e[i].v--;
    adj[e[i].u].push_back(i);
    adj[e[i].v].push_back(i);
  }
  bool ok = 1;
  for (int u = 0; u < (int)(n); u++)
    if (!lvl[u]) {
      cycle.clear();
      lvl[u] = 1;
      pre[u] = -1;
      dfs1(u);
      if (cycle.empty()) {
        ok &= dfs2(u, -1) == 0;
      } else {
        auto delta = dfs2(root, -1) / 2;
        for (auto ind : cycle) {
          ans[ind] += delta;
          delta = -delta;
        }
      }
    }
  if (ok) {
    cout << "YES\n";
    for (int i = 0; i < (int)(m); i++) cout << ans[i] << '\n';
  } else
    cout << "NO\n";
  return 0;
}
