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 = 1e5 + 10;
long long n, m, from[MAXN], to[MAXN], w[MAXN], sum[MAXN];
vector<int> adj[MAXN];
int col[MAXN];
int root = -1;
int sec[MAXN], sz;
int tv = -1;
void dfs(int v, int c = 1, int p = -1) {
  if (col[v]) {
    if (col[v] != c) {
      root = v;
      sec[sz++] = p;
      tv = v;
    }
    return;
  }
  col[v] = c;
  for (int e : adj[v]) {
    int u = from[e] ^ to[e] ^ v;
    dfs(u, 3 - c, e);
    if (root != -1) {
      if (v == tv) tv = -1;
      if (tv != -1) sec[sz++] = p;
      return;
    }
  }
}
int par[MAXN], q[MAXN], h, t, cnt[MAXN];
void dfs2(int v, int p = -1) {
  col[v] = 1;
  par[v] = p;
  for (int e : adj[v])
    if (e ^ p) {
      int u = from[e] ^ to[e] ^ v;
      if (!col[u]) {
        dfs2(u, e);
        cnt[v]++;
      }
    }
  if (!cnt[v]) q[t++] = v;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> sum[i];
  for (int i = 0; i < m; i++) {
    cin >> from[i] >> to[i], from[i]--, to[i]--;
    adj[from[i]].push_back(i);
    adj[to[i]].push_back(i);
    w[i] = 1;
    sum[from[i]] -= 1;
    sum[to[i]] -= 1;
  }
  dfs(0);
  if (root == -1) root = 0;
  memset(col, 0, sizeof(col));
  dfs2(root);
  while (t - h) {
    int v = q[h++];
    if (v == root) break;
    w[par[v]] += sum[v];
    int p = from[par[v]] ^ to[par[v]] ^ v;
    sum[p] -= sum[v];
    sum[v] = 0;
    cnt[p]--;
    if (cnt[p] == 0) q[t++] = p;
  }
  if (sum[root] == 0) {
    cout << "YES\n";
    for (int i = 0; i < m; i++) cout << w[i] << "\n";
  } else {
    if (sz == 0)
      cout << "NO\n";
    else {
      assert((sum[root] & 1) == 0);
      for (int i = 0; i < sz; i++)
        w[sec[i]] += (i & 1 ? -sum[root] / 2 : sum[root] / 2);
      cout << "YES\n";
      for (int i = 0; i < m; i++) cout << w[i] << "\n";
    }
  }
  return 0;
}
