2 1
1 1
2 1
 8 12
-6 2 -3 2 6 -7 1 -5
2 1
5 6
1 6
1 4
8 2
2 7
2 5
8 3
8 4
3 7
7 6
3 1
 10 13
3 4 -3 8 6 4 -5 1 3 -7
9 5
9 2
10 3
1 4
3 5
9 1
6 10
10 4
3 1
2 7
1 6
1 7
7 8
 43 52
-23 -18 -35 21 -12 38 -35 -11 28 -20 27 -5 9 -19 -39 -25 -32 32 -36 28 11 37 1 -25 -22 9 -15 21 25 -39 10 36 -30 -40 22 26 25 -27 -22 -38 -1 18 -13
33 40
31 23
30 26
21 17
6 2
41 19
32 39
32 23
13 14
25 35
31 30
19 32
25 22
34 36
7 40
23 6
40 12
1 3
23 43
36 13
18 33
17 32
7 3
21 34
41 35
20 7
23 1
41 8
25 19
20 29
42 5
40 21
9 37
17 41
30 10
41 18
39 1
20 24
20 4
42 3
20 25
5 16
31 9
42 28
10 11
19 42
31 38
25 2
31 27
17 25
13 15
31 20
 2 1
1 1
1 2
 5 7
4 1 5 3 -1
2 4
5 4
5 2
1 5
1 2
4 1
1 3
 10 12
5 1 1 8 -8 10 -3 -2 1 7
5 3
8 2
10 9
4 6
5 6
4 5
5 10
4 7
8 4
3 1
3 6
6 10
 20 40
-9 -10 -9 15 -3 -5 -17 -10 -6 2 -13 19 10 -15 15 -14 17 0 7 -8
3 17
6 18
15 12
2 5
18 3
16 20
6 17
20 10
10 18
9 12
15 3
6 4
15 16
20 6
20 9
9 4
4 8
14 5
11 7
12 11
3 13
14 19
7 17
16 14
19 7
12 13
14 13
13 11
9 14
13 17
8 19
5 20
2 17
2 16
12 5
8 1
20 3
6 2
5 18
13 8

YES
                                                               1
 NO
 YES
                                                              -7
                                                              10
                                                             -16
                                                               3
                                                              13
                                                               0
                                                               4
                                                               5
                                                               0
                                                              -6
                                                               0
                                                               0
                                                               1
 NO
 YES
                                                               1
 YES
                                                               2
                                                               1
                                                              -1
                                                              -1
                                                               0
                                                               0
                                                               5
 YES
-4
1
1
17
-7
-3
6
-3
-3
5
0
0
 YES
                                                             -30
                                                             -21
                                                             -23
                                                             -10
                                                              21
                                                             -52
                                                               0
                                                               2
                                                               0
                                                              -9
                                                               0
                                                              16
                                                              38
                                                               0
                                                              42
                                                               0
                                                              -1
                                                               7
                                                             -64
                                                              51
                                                               0
                                                               7
                                                              47
                                                               0
                                                               0
                                                               0
                                                              10
                                                               0
                                                             -39
                                                               0
                                                               0
                                                               0
                                                               0
                                                               0
                                                               0
                                                              -9
                                                               0
                                                               0
                                                               0
                                                               0

#include <bits/stdc++.h>
using namespace std;
const int maxn = 100010;
int n, m, u[maxn], v[maxn], vis[maxn], dep[maxn], fa[maxn], id[maxn];
long long c[maxn], ans[maxn];
bool mark[maxn];
vector<pair<int, int>> G[maxn];
int main() {
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; i++) {
    scanf("%lld", &c[i]);
  }
  for (int i = 1; i <= m; i++) {
    scanf("%d %d", &u[i], &v[i]);
    c[u[i]]--, c[v[i]]--, ans[i] = 1;
    G[u[i]].emplace_back(v[i], i);
    G[v[i]].emplace_back(u[i], i);
  }
  function<void(int, int)> dfs = [&](int v, int f) {
    vis[v] = 1, fa[v] = f, dep[v] = dep[f] + 1;
    for (auto u : G[v])
      if (!vis[u.first]) {
        id[u.first] = u.second, dfs(u.first, v);
      }
    if (v > 1 && c[v]) {
      c[fa[v]] -= c[v], ans[id[v]] += c[v], c[v] = 0;
    }
  };
  dfs(1, 0);
  for (auto u : G[1])
    if (G[u.first].size() > 1) {
      ans[id[u.first]] += c[1], c[u.first] -= c[1], c[1] = 0;
    }
  auto get = [&](int u, int v) { return dep[u] > dep[v] ? id[u] : id[v]; };
  memset(vis, 0, sizeof(vis));
  auto solve = [&](int i) {
    vector<int> V1, V2;
    while (u[i] ^ v[i]) {
      if (dep[u[i]] > dep[v[i]]) {
        if (mark[id[u[i]]]) return;
        mark[id[u[i]]] = 1;
        vis[u[i]] = 1, V1.push_back(u[i]), u[i] = fa[u[i]];
      } else {
        if (mark[id[v[i]]]) return;
        mark[id[v[i]]] = 1;
        vis[v[i]] = 1, V2.push_back(v[i]), v[i] = fa[v[i]];
      }
    }
    V1.push_back(u[i]);
    reverse(V2.begin(), V2.end());
    for (int x : V2) V1.push_back(x);
    long long sum = 0;
    for (int x : V1) sum += c[x];
    assert(!(sum & 1)), sum >>= 1;
    for (int i = 1; i < V1.size() - 1; i++)
      if (c[V1[i]]) {
        ans[get(V1[i], V1[i + 1])] += c[V1[i]];
        c[V1[i + 1]] -= c[V1[i]], c[V1[i]] = 0;
      }
    if (c[V1.back()]) {
      ans[i] += c[V1.back()];
      c[V1[0]] -= c[V1.back()], c[V1.back()] = 0;
    }
    if (c[V1[0]]) {
      ans[get(V1[0], V1[1])] += c[V1[0]] / 2;
      c[V1[1]] -= c[V1[0]] / 2, c[V1[0]] /= 2;
    }
    for (int i = 1; i < V1.size() - 1; i++)
      if (c[V1[i]]) {
        ans[get(V1[i], V1[i + 1])] += c[V1[i]];
        c[V1[i + 1]] -= c[V1[i]], c[V1[i]] = 0;
      }
    if (c[V1.back()]) {
      ans[i] += c[V1.back()];
      c[V1[0]] -= c[V1.back()], c[V1.back()] = 0;
    }
    for (int x : V1) assert(!c[x]);
  };
  function<void(int)> dfs2 = [&](int v) {
    for (auto u : G[v])
      if (dep[u.first] > dep[v] && (dep[v] - dep[u.first]) % 2 == 0) {
        solve(u.second);
      }
    for (auto u : G[v])
      if (dep[u.first] == dep[v] + 1) {
        dfs2(u.first);
      }
  };
  dfs2(1);
  for (int i = 1; i <= n; i++) {
    if (c[i]) printf("NO\n"), exit(0);
  }
  printf("YES\n");
  for (int i = 1; i <= m; i++) {
    printf("%lld\n", ans[i]);
  }
  return 0;
}
