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 INF = 1LL << 60;
bool vis[100005];
int to[200005];
long long deg[100005];
int dep[100005];
vector<int> G[100005];
long long used[200005];
long long rem[100005];
void dfs(int v, int par, int ce) {
  vis[v] = true;
  dep[v] = dep[par] + 1;
  rem[v] = deg[v];
  for (int k = 0; k < (G[v].size()); k++) {
    int e = G[v][k], u = to[e];
    if (u == par || vis[u]) continue;
    dfs(u, v, e ^ 1);
    rem[v] -= used[e];
  }
  if (ce != -1) {
    used[ce] = used[ce ^ 1] = rem[v];
    rem[v] = 0;
  }
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int k = 1; k <= (n); k++) scanf("%I64d", &deg[k]);
  for (int k = 0; k < (m); k++) {
    int u, v;
    scanf("%d%d", &u, &v);
    G[u].push_back(k << 1);
    G[v].push_back(k << 1 | 1);
    to[k + k] = v;
    to[k + k + 1] = u;
  }
  memset(vis, false, sizeof(vis));
  dfs(1, 0, -1);
  for (int k = 0; k < (m); k++) {
    int u = to[k << 1], v = to[k << 1 | 1];
    if (used[k << 1] != 0LL || (dep[u] - dep[v]) & 1) continue;
    int cd = rem[1] >> 1;
    if (!(dep[u] & 1)) cd = -cd;
    used[k << 1] = used[k << 1 | 1] = cd;
    deg[u] -= cd;
    deg[v] -= cd;
    break;
  }
  memset(vis, false, sizeof(vis));
  dfs(1, 0, -1);
  if (rem[1] == 0LL) {
    printf("YES\n");
    for (int k = 0; k < (m); k++) printf("%I64d\n", used[k << 1]);
  } else
    printf("NO\n");
  return 0;
}
