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;
struct node {
  int to, ind;
  node *next;
};
struct rec {
  int l, r;
};
int i, j, m, n, c[100005], x, y, dep[100005], ans[100005], now[100005];
int u, dif, faind[100005], father[100005], temp, tt;
rec edge[100005];
node *nd[100005];
bool visit[100005];
void addd(int u, int v, int ind) {
  node *p = new node();
  p->to = v;
  p->ind = ind;
  p->next = nd[u];
  nd[u] = p;
}
void dfs(int u, int pre, int ind) {
  node *p = nd[u];
  visit[u] = true;
  int temp = 0;
  while (p) {
    if (!visit[p->to]) {
      dep[p->to] = dep[u] + 1;
      faind[p->to] = p->ind;
      father[p->to] = u;
      dfs(p->to, u, p->ind);
      temp += ans[p->ind];
    }
    p = p->next;
  }
  ans[ind] = c[u] - temp;
  now[u] = temp;
}
int main() {
  scanf("%d%d", &n, &m);
  for (i = 1; i <= n; i++) {
    scanf("%d", &c[i]);
  }
  for (i = 1; i <= m; i++) {
    scanf("%d%d", &x, &y);
    edge[i].l = x;
    edge[i].r = y;
    addd(x, y, i);
    addd(y, x, i);
  }
  dep[1] = 0;
  dfs(1, -1, 0);
  dif = (c[1] - now[1]) / 2;
  if (c[1] == now[1]) {
    printf("YES\n");
    for (i = 1; i <= m; i++) {
      printf("%d\n", ans[i]);
    }
    return 0;
  }
  for (i = 1; i <= m; i++) {
    if ((dep[edge[i].l] & 1) == (dep[edge[i].r] & 1)) {
      if ((dep[edge[i].l] & 1) == 0) {
        ans[i] = dif;
        tt = -dif;
      } else {
        ans[i] = -dif;
        tt = dif;
      }
      u = edge[i].l;
      temp = tt;
      while (u > 1) {
        ans[faind[u]] += temp;
        temp = -temp;
        u = father[u];
      }
      u = edge[i].r;
      temp = tt;
      while (u > 1) {
        ans[faind[u]] += temp;
        temp = -temp;
        u = father[u];
      }
      printf("YES\n");
      for (j = 1; j <= m; j++) {
        printf("%d\n", ans[j]);
      }
      return 0;
    }
  }
  printf("NO\n");
  return 0;
}
