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 maxn = 100009;
struct E {
  int u, v;
  long long val;
} edges[maxn];
vector<int> neigh[maxn];
long long val[maxn];
int be = -1;
int depth[maxn];
long long cur_val[maxn];
void dfs(int v, int p) {
  int bck;
  for (int i : neigh[v]) {
    int u = (edges[i].v == v ? edges[i].u : edges[i].v);
    if (u == p) {
      bck = i;
    } else if (depth[u] == -1) {
      depth[u] = depth[v] + 1;
      dfs(u, v);
    } else if (depth[u] < depth[v]) {
      if ((depth[u] + depth[v]) % 2 == 0) {
        be = i;
      }
    }
  }
  if (v != 1) {
    edges[bck].val = cur_val[v];
    cur_val[p] -= cur_val[v];
  }
}
int main() {
  ios::sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> val[i];
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    edges[i].u = u;
    edges[i].v = v;
    neigh[u].push_back(i);
    neigh[v].push_back(i);
  }
  memset(depth, -1, sizeof depth);
  memcpy(cur_val, val, sizeof val);
  depth[1] = 0;
  dfs(1, 0);
  if (cur_val[1] != 0) {
    if (be == -1 || cur_val[1] % 2 != 0) {
      cout << "NO";
      return 0;
    }
    for (int i = 0; i < m; i++) edges[i].val = 0;
    if (depth[edges[be].u] % 2 == 0)
      edges[be].val = cur_val[1] / 2;
    else
      edges[be].val = -cur_val[1] / 2;
    val[edges[be].u] -= edges[be].val;
    val[edges[be].v] -= edges[be].val;
    memset(depth, -1, sizeof depth);
    memcpy(cur_val, val, sizeof val);
    depth[1] = 0;
    dfs(1, 0);
  }
  cout << "YES\n";
  for (int i = 0; i < m; i++) cout << edges[i].val << "\n";
}
