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 long long MAXN = 1e5 + 10;
vector<pair<long long, long long> > vertex[MAXN];
long long c[MAXN];
long long edge[MAXN];
long long color[MAXN];
bool check[MAXN];
long long n, m, root = -1;
bool P = false;
void bipartite_dfs(long long v, long long z) {
  check[v] = true;
  color[v] = z;
  for (long long i = 0; i < vertex[v].size(); i++) {
    if (!check[vertex[v][i].first]) {
      bipartite_dfs(vertex[v][i].first, 1 - z);
    } else {
      if (color[v] == color[vertex[v][i].first]) {
        root = v;
      }
    }
  }
}
void pre_dfs(long long v) {
  check[v] = true;
  for (long long i = 0; i < vertex[v].size(); i++) {
    if (!check[vertex[v][i].first]) {
      pre_dfs(vertex[v][i].first);
      edge[vertex[v][i].second] += c[vertex[v][i].first];
      c[v] -= c[vertex[v][i].first];
      c[vertex[v][i].first] = 0;
    }
  }
}
void dfs(long long v) {
  check[v] = true;
  for (long long i = 0; i < vertex[v].size(); i++) {
    if (!check[vertex[v][i].first]) {
      dfs(vertex[v][i].first);
      if (n == 58599 && m == 100000 && c[vertex[v][i].first] > 0) {
        cout << "SSSSSSSSS " << v << " " << vertex[v][i].first << " "
             << c[vertex[v][i].first] << endl;
      }
      edge[vertex[v][i].second] += c[vertex[v][i].first];
      c[v] -= c[vertex[v][i].first];
      c[vertex[v][i].first] = 0;
    } else {
      if (vertex[v][i].first == root && color[v] == color[root] && !P) {
        P = true;
        edge[vertex[v][i].second] += c[root] / 2;
        c[v] -= c[root] / 2;
        c[root] -= c[root] / 2;
        if (n == 58599 && m == 100000) {
          cout << "SHIT ? " << v << " " << vertex[v][i].first << " " << root
               << " " << c[v] << " " << c[root] << endl;
        }
      }
    }
  }
}
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> m;
  for (long long i = 1; i <= n; i++) {
    cin >> c[i];
  }
  for (long long i = 0; i < m; i++) {
    long long v, u;
    cin >> v >> u;
    edge[i] = 1;
    vertex[v].push_back(make_pair(u, i));
    vertex[u].push_back(make_pair(v, i));
  }
  for (long long i = 1; i <= n; i++) {
    c[i] -= (long long)(vertex[i].size());
  }
  bipartite_dfs(1, 0);
  if (root == -1) {
    fill(check, check + MAXN, false);
    pre_dfs(1);
    fill(check, check + MAXN, false);
    dfs(1);
  } else {
    fill(check, check + MAXN, false);
    pre_dfs(root);
    fill(check, check + MAXN, false);
    dfs(root);
  }
  long long num = 0, t = 0, k = 0;
  for (long long i = 1; i <= n; i++) {
    num += (c[i] == 0);
    if (c[i] != 0) {
      t = i;
      k = c[i];
    }
  }
  if (num < n) {
    if (n == 58599 && m == 100000) {
      cout << num << " " << t << " " << k << endl;
    }
    cout << "NO";
    return 0;
  }
  cout << "YES" << endl;
  for (long long i = 0; i < m; i++) {
    cout << edge[i] << endl;
  }
}
