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 MOD = 1000000007;
vector<pair<int, int> > adj[111111];
int color[111111];
vector<pair<int, int> > odd_cycle;
pair<bool, int> find_odd_cycle(int v, int c) {
  color[v] = c;
  for (auto p : adj[v]) {
    if (color[p.first] == c) {
      odd_cycle.push_back(p);
      return {true, p.first};
    } else if (!color[p.first]) {
      auto res = find_odd_cycle(p.first, 3 - c);
      if (res.first) {
        if (res.second != -1) odd_cycle.push_back(p);
        if (res.second == v) res.second = -1;
        return res;
      }
    }
  }
  return {false, -1};
}
long long C[111111];
long long out[111111];
bool visited[111111];
long long assign_values(int v) {
  visited[v] = true;
  for (auto p : adj[v])
    if (!visited[p.first]) {
      long long required = assign_values(p.first);
      C[v] -= required;
      C[p.first] -= required;
      out[p.second] += required;
    }
  return C[v];
}
pair<int, int> E[111111];
int main() {
  ios_base::sync_with_stdio(0);
  int N, M;
  cin >> N >> M;
  for (int i = (1); i < (N + 1); ++i) cin >> C[i];
  for (int i = 0; i < (M); ++i) {
    cin >> E[i].first >> E[i].second;
    adj[E[i].first].push_back({E[i].second, i});
    adj[E[i].second].push_back({E[i].first, i});
  }
  bool has_odd_cycle = find_odd_cycle(1, 1).first;
  int r = has_odd_cycle ? odd_cycle[0].first : 1;
  long long required = assign_values(r);
  if (required && !has_odd_cycle) {
    cout << "NO" << endl;
    return 0;
  }
  if (required) {
    for (int i = 0; i < (odd_cycle.size()); ++i) {
      out[odd_cycle[i].second] -= (i % 2 == 0 ? -1 : 1) * required / 2;
    }
  }
  cout << "YES" << endl;
  for (int i = 0; i < (M); ++i) cout << out[i] << endl;
}
