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 double pi = acosl(-1);
const int maxn = 100010;
const long long mod = 1e9 + 7;
const long long inf = 1e18;
const long double eps = 1e-10;
int n, m, u, v, vis[maxn], root, vise[maxn], depth[maxn];
long long w[maxn], c[maxn];
vector<pair<int, int> > g[maxn];
pair<int, int> edge[maxn], fa[maxn];
void dfs1(int cur, int p, int col) {
  if (vis[cur]) {
    if (vis[cur] != col) root = cur;
    return;
  }
  vis[cur] = col;
  for (pair<int, int> pa : g[cur]) {
    if (pa.first != p) dfs1(pa.first, cur, -col);
  }
}
void dfs2(int cur, int p, int id, int dep) {
  if (vis[cur]) return;
  vis[cur] = 1;
  long long wt = 0;
  for (pair<int, int> pa : g[cur]) {
    if (pa.first != p)
      dfs2(pa.first, cur, pa.second, dep + 1), wt += w[pa.second];
  }
  w[id] = c[cur] - wt;
  vise[id] = 1;
  fa[cur] = {id, p};
  depth[cur] = dep;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i < n + 1; i++) scanf("%lld", &c[i]);
  for (int i = 1; i < m + 1; i++) {
    scanf("%d%d", &u, &v);
    g[u].push_back({v, i}), g[v].push_back({u, i});
    edge[i] = {u, v};
  }
  root = 1;
  dfs1(1, 0, 1);
  memset(vis, 0, sizeof(vis));
  dfs2(root, 0, 0, 0);
  if (w[0]) {
    for (int i = 1; i < m + 1; i++)
      if (!vise[i]) {
        u = edge[i].first, v = edge[i].second;
        if ((depth[u] & 1) == (depth[v] & 1)) {
          int sgn = 1;
          if (depth[u] & 1) sgn = -1;
          long long diff = w[0] / 2;
          w[i] = diff * sgn;
          while (u) sgn = -sgn, w[fa[u].first] += sgn * diff, u = fa[u].second;
          sgn = 1;
          if (depth[v] & 1) sgn = -1;
          while (v) sgn = -sgn, w[fa[v].first] += sgn * diff, v = fa[v].second;
          break;
        }
      }
  }
  if (w[0])
    printf("NO\n");
  else {
    printf("YES\n");
    for (int i = 1; i < m + 1; i++) printf("%lld\n", w[i]);
  }
}
