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;
vector<vector<int> > adj;
map<int, map<int, long long int> > wei;
vector<int> fa;
long long int we[100020];
int ro = 0, nro, nro1;
vector<int> vis;
long long int w[2];
void dfs(int v, int pa) {
  vis[v] = pa;
  w[pa] += we[v];
  for (int j = 0; j < adj[v].size(); j++) {
    if (vis[adj[v][j]] == -1) {
      dfs(adj[v][j], !pa);
    } else if (vis[adj[v][j]] == pa && ro == 0) {
      ro = v;
      nro = adj[v][j];
    }
  }
}
void dfsSolve(int pre, int v) {
  fa[v] = pre;
  vis[v] = 1;
  for (int i = 0; i < adj[v].size(); i++) {
    if (vis[adj[v][i]] == 0) {
      if (!((v == pre) && adj[v][i] == nro)) dfsSolve(v, adj[v][i]);
    }
  }
  if (v != pre) {
    wei[v][pre] -= we[v];
    wei[pre][v] -= we[v];
    we[pre] -= we[v];
  }
}
int main() {
  int n, m;
  cin >> n >> m;
  fa.assign(n + 2, 0);
  vector<int> emp;
  adj.assign(n + 2, emp);
  vis.assign(n + 2, -1);
  int ea[100020], eb[100020];
  for (int j = 0; j < n; j++) {
    cin >> we[j + 1];
  }
  for (int j = 0; j < m; j++) {
    cin >> ea[j] >> eb[j];
    adj[ea[j]].push_back(eb[j]);
    adj[eb[j]].push_back(ea[j]);
  }
  dfs(1, 1);
  int ch = 0;
  vis.clear();
  vis.assign(n + 2, 0);
  if (ro == 0) {
    if (w[0] == w[1]) {
      dfsSolve(1, 1);
    } else
      ch = 1;
  } else {
    nro1 = nro;
    dfsSolve(ro, ro);
    int x = we[ro] / 2;
    int t = 1;
    wei[ro][nro] += -x;
    wei[nro][ro] += -x;
    while (fa[nro] != nro) {
      wei[nro][fa[nro]] += t * x;
      wei[fa[nro]][nro] += t * x;
      t *= -1;
      nro = fa[nro];
    }
  }
  if (ch == 0) {
    cout << "YES" << endl;
    if (n == 206) {
      cout << ro << " " << nro1 << endl;
    }
    for (int i = 0; i < m; i++) {
      cout << wei[ea[i]][eb[i]] * -1 << endl;
    }
  } else
    cout << "NO" << endl;
  return 0;
}
