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 N = 3e5;
int n, m, head[N], cnt, dep[N], fa[N], pid[N];
long long c[N], val[N];
bool vis[N], use[N];
struct edge {
  int to, nxt, id;
} e[N << 1];
void finish() {
  cout << "YES\n";
  for (int i = 1; i <= m; ++i) cout << val[i] << '\n';
  exit(0);
}
void dfs(int u) {
  vis[u] = 1;
  for (int i = head[u]; i; i = e[i].nxt)
    if (!vis[e[i].to]) {
      fa[e[i].to] = u;
      dep[e[i].to] = dep[u] + 1;
      pid[e[i].to] = e[i].id;
      use[e[i].id] = 1;
      dfs(e[i].to);
    }
  if (u != 1) {
    val[pid[u]] = c[u];
    c[fa[u]] -= c[u];
    c[u] = 0;
  }
}
void dfs2(int u) {
  for (int i = head[u]; i; i = e[i].nxt)
    if (!use[e[i].id] && (dep[e[i].to] - dep[u]) % 2 == 0) {
      assert(dep[e[i].to] > dep[u]);
      int fh = dep[u] % 2;
      long long dlt = c[1] / 2;
      if (fh == 1) dlt *= -1;
      val[e[i].id] = dlt;
      c[u] -= dlt, c[e[i].to] -= dlt;
      for (int v = e[i].to; v != 1; v = fa[v]) {
        val[pid[v]] += c[v];
        c[fa[v]] -= c[v];
        c[v] = 0;
      }
      assert(!c[1]);
      finish();
    }
  for (int i = head[u]; i; i = e[i].nxt)
    if (use[e[i].id] && dep[e[i].to] > dep[u]) dfs2(e[i].to);
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> m;
  for (int i = 1; i <= n; ++i) cin >> c[i];
  for (int i = 1; i <= m; ++i) {
    int u, v;
    cin >> u >> v;
    e[++cnt] = (edge){v, head[u], i}, head[u] = cnt;
    e[++cnt] = (edge){u, head[v], i}, head[v] = cnt;
  }
  dfs(1);
  if (c[1] % 2 == 0) {
    if (c[1])
      dfs2(1);
    else
      finish();
  }
  cout << "NO\n";
  return 0;
}
