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>
const int N = 100005;
int n, m, head[N], id[N], c[N], tot = 1;
long long weight[N];
struct edge {
  int to, nxt;
} e[N << 1];
int fa[N];
int find(int x) { return x == fa[x] ? x : fa[x] = find(fa[x]); }
void link(int x, int y) {
  e[++tot] = (edge){y, head[x]}, head[x] = tot;
  e[++tot] = (edge){x, head[y]}, head[y] = tot;
}
int f[N], g[N], dep[N];
void dfs(int x) {
  weight[g[x]] = c[x];
  for (int i = head[x]; i; i = e[i].nxt)
    if (e[i].to != f[x]) {
      f[e[i].to] = x, g[e[i].to] = id[i >> 1];
      dep[e[i].to] = dep[x] + 1, dfs(e[i].to);
      weight[g[x]] -= weight[g[e[i].to]];
    }
}
int u[N], v[N];
int main() {
  std::ios::sync_with_stdio(0), std::cin.tie(0);
  std::cin >> n >> m;
  for (int i = 1; i <= n; ++i) fa[i] = i, std::cin >> c[i];
  for (int i = 1; i <= m; ++i) {
    static int cnt = 0;
    std::cin >> u[i] >> v[i];
    if (find(u[i]) != find(v[i])) {
      id[++cnt] = i, link(u[i], v[i]);
      fa[find(u[i])] = find(v[i]);
    }
  }
  dfs(1);
  for (int i = 1; i <= m; ++i)
    if (!(dep[u[i]] - dep[v[i]] & 1)) {
      long long t = weight[0] / 2;
      weight[0] = 0;
      if (dep[u[i]] & 1) t = -t;
      long long s = weight[i] = t;
      for (int j = u[i]; j > 1; j = f[j]) weight[g[j]] += s = -s;
      for (int j = v[i]; j > 1; j = f[j]) weight[g[j]] += t = -t;
      break;
    }
  if (weight[0]) return std::cout << "NO\n", 0;
  std::cout << "YES\n";
  for (int i = 1; i <= m; ++i) std::cout << weight[i] << '\n';
  return 0;
}
