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 edge {
  int to, next, id;
} e[100005 * 2];
int n, m, tot, idx, idy, ide;
int head[100005], c[100005], vis[100005];
long long a[100005], b[100005];
void add(int x, int y, int id) {
  e[++tot] = (edge){y, head[x], id};
  head[x] = tot;
}
bool pdfs(int x) {
  for (int i = head[x]; i; i = e[i].next)
    if (!c[e[i].to]) {
      c[e[i].to] = 3 - c[x];
      if (!pdfs(e[i].to)) return 0;
    } else if (c[e[i].to] == c[x]) {
      idx = x;
      idy = e[i].to;
      ide = i;
      return 0;
    }
  return 1;
}
long long dfs(int x) {
  vis[x] = 1;
  long long s = a[x];
  for (int i = head[x]; i; i = e[i].next)
    if (!vis[e[i].to]) {
      long long tmp = dfs(e[i].to);
      b[e[i].id] += tmp;
      s -= tmp;
    }
  return s;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%I64d", &a[i]);
  for (int i = 1; i <= m; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    add(x, y, i);
    add(y, x, i);
  }
  c[1] = 1;
  bool f = pdfs(1);
  if (f) {
    long long s = 0;
    for (int i = 1; i <= n; i++)
      if (c[i] == 1)
        s += a[i];
      else
        s -= a[i];
    if (s) return puts("NO"), 0;
    s = dfs(1);
    if (s) return puts("NO"), 0;
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%I64d\n", b[i]);
    return 0;
  }
  long long s = dfs(1);
  if (s & 1) return puts("NO"), 0;
  s /= 2;
  if (c[idx] == 2) s = -s;
  memset(b, 0, sizeof(b));
  b[e[ide].id] = s;
  a[idx] -= s;
  a[idy] -= s;
  memset(vis, 0, sizeof(vis));
  s = dfs(1);
  if (s) return puts("NO"), 0;
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%I64d\n", b[i]);
}
