#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int head[N], nxt[N << 1], to[N << 1], E;
long long ans[N];
long long val[N];
int vst[N], dep[N];
int fa[N];
vector<int> path;
void dfs(int u) {
  for (int e = head[u]; ~e && path.empty(); e = nxt[e]) {
    int v = to[e];
    if (vst[v]) {
      if (vst[v] == vst[u]) {
        int U = u, V = v;
        while (dep[U] > dep[V]) {
          path.push_back(U);
          U = fa[U];
        }
        stack<int> a;
        while (dep[V] > dep[U]) {
          a.push(V);
          V = fa[V];
        }
        while (true) {
          path.push_back(U);
          if (U != V) {
            a.push(V);
          }
          U = fa[U];
          V = fa[V];
          break;
        }
        while (!a.empty()) {
          path.push_back(a.top());
          a.pop();
        }
      }
    } else {
      vst[v] = vst[u] ^ 1;
      fa[v] = u;
      dep[v] = dep[u] + 1;
      dfs(v);
    }
  }
}
void rdfs(int u) {
  vst[u] = 1;
  for (int e = head[u]; ~e; e = nxt[e]) {
    int v = to[e];
    if (vst[v]) {
      continue;
    }
    rdfs(v);
    ans[e >> 1] = val[v];
    val[u] -= val[v];
  }
}
int main() {
  memset(head, -1, sizeof head);
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; i++) {
    scanf("%I64d", val + i);
  }
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d %d", &u, &v);
    nxt[E] = head[u];
    to[E] = v;
    head[u] = E++;
    nxt[E] = head[v];
    to[E] = u;
    head[v] = E++;
  }
  vst[1] = 2;
  dfs(1);
  memset(vst, 0, sizeof vst);
  if (path.empty()) {
    rdfs(1);
    if (val[1]) {
      puts("NO");
      return 0;
    }
  } else {
    for (auto u : path) {
      vst[u] = 2;
    }
    long long tot = 0;
    long long crr = 0;
    for (int i = 0; i < path.size(); i++) {
      rdfs(path[i]);
      tot += val[path[i]];
      if (i > 1 && !(i & 1)) {
        crr += val[path[i]];
      }
    }
    if (tot & 1) {
      puts("NO");
      return 0;
    }
    tot >>= 1;
    for (int i = 0; i < path.size(); i++) {
      int u = path[i];
      int v = i + 1 < path.size() ? path[i + 1] : path[0];
      for (int e = head[u]; ~e; e = nxt[e]) {
        if (to[e] == v) {
          ans[e >> 1] = tot - crr;
          break;
        }
      }
      crr = tot * 2 - crr - val[v];
    }
  }
  puts("YES");
  for (int i = 0; i < m; i++) {
    printf("%I64d\n", ans[i]);
  }
  return 0;
}
