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 N = 100000 + 10;
const int M = N;
long long c[N];
int vis[N];
vector<int> adj[N], radj[N];
struct node {
  int u, v;
  node(int u = 0, int v = 0) : u(u), v(v) { makegood(); }
  void makegood() {
    if (u > v) swap(u, v);
  }
  bool operator<(const node &rhs) const {
    if (u != rhs.u) return u < rhs.u;
    return v < rhs.v;
  }
} E[M];
int fu = -1, fv = -1;
map<node, long long> Ans;
int indeg[N];
void dfs(int u, int p, int flg) {
  vis[u] = flg + 1;
  for (auto v : adj[u]) {
    if (!vis[v]) {
      dfs(v, u, !flg);
      radj[v].push_back(u);
      ++indeg[u];
    } else if (vis[v] == vis[u])
      fu = u, fv = v;
  }
}
long long sum[3];
int q[N], qh, qt;
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%lld", &c[i]);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    adj[u].push_back(v);
    adj[v].push_back(u);
    E[i] = node(u, v);
  }
  dfs(1, -1, 0);
  for (int i = 1; i <= n; i++) {
    assert(vis[i]);
    sum[vis[i]] += c[i];
  }
  if (fu == -1 && sum[1] != sum[2]) {
    puts("NO");
    return 0;
  }
  long long R = sum[2];
  if (fu != -1) {
    long long S = sum[1] - sum[2];
    if (vis[fu] == 2) S = -S, R = sum[1];
    assert(S % 2 == 0);
    Ans[node(fu, fv)] = S / 2;
    c[fu] -= S / 2, c[fv] -= S / 2;
  }
  memset(vis, 0, sizeof vis);
  for (int i = 1; i <= n; i++)
    if (!indeg[i]) q[qt++] = i;
  while (qh < qt) {
    int u = q[qh++];
    for (auto v : radj[u]) {
      c[v] -= c[u];
      Ans[node(u, v)] = c[u];
      if (--indeg[v] == 0) q[qt++] = v;
    }
  }
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%lld\n", Ans[E[i]]);
  return 0;
}
