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 = 2e6 + 5;
int n, m;
vector<pair<long long, int> > g[N];
long long ans[N];
bool vis[N], used[N];
int h[N], fa[N], lab[N], c[N];
void dfs(int u) {
  vis[u] = true;
  for (auto it : g[u]) {
    int v = it.first, id = it.second;
    if (vis[v]) continue;
    fa[v] = u;
    lab[v] = id;
    h[v] = h[u] + 1;
    dfs(v);
    used[id] = true;
    if (c[v]) c[u] -= c[v], ans[id] += c[v], c[v] = 0;
  }
}
pair<long long, int> e[N];
void gao(int u, int v, int cur, int f, long long val) {
  vector<int> p;
  p.push_back(cur);
  while (v != u) {
    p.push_back(lab[v]);
    v = fa[v];
  }
  for (auto it : p) {
    if (f)
      ans[it] += val;
    else
      ans[it] -= val;
    f = 1 - f;
  }
  f = 1 - f;
  while (u != 1) {
    if (!f)
      ans[lab[u]] += 2 * val;
    else
      ans[lab[u]] -= 2 * val;
    u = fa[u];
  }
}
int main() {
  cin >> n >> m;
  for (int i = (1); i < (n + 1); i++) cin >> c[i];
  int u, v;
  for (int i = (1); i < (m + 1); i++) {
    cin >> u >> v;
    e[i] = pair<long long, int>(u, v);
    g[u].push_back(pair<long long, int>(v, i));
    g[v].push_back(pair<long long, int>(u, i));
  }
  dfs(1);
  if (abs(c[1]) & 1) {
    cout << "NO\n";
    return 0;
  }
  if (c[1] == 0) {
    cout << "YES\n";
    for (int i = (1); i < (m + 1); i++) cout << ans[i] << "\n";
    return 0;
  }
  for (int i = (1); i < (m + 1); i++) {
    if (used[i]) continue;
    u = e[i].first, v = e[i].second;
    if (h[u] > h[v]) swap(u, v);
    if ((h[u] + h[v]) % 2 == 0) {
      if (c[1] > 0) {
        if (h[u] & 1) {
          gao(u, v, i, 0, abs(c[1]) / 2);
        } else {
          gao(u, v, i, 1, abs(c[1]) / 2);
        }
      } else if (c[1] < 0) {
        if (h[u] & 1) {
          gao(u, v, i, 1, abs(c[1]) / 2);
        } else {
          gao(u, v, i, 0, abs(c[1]) / 2);
        }
      }
      cout << "YES\n";
      for (int j = (1); j < (m + 1); j++) cout << ans[j] << "\n";
      return 0;
    }
  }
  cout << "NO\n";
  return 0;
}
