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;
int n, m, f[100010], tot = 1, head[100010], col[100010], spe, root;
int bk[100010], v[100010];
long long a[100010], w[100010];
bool flag[100010];
inline int find(int x) {
  if (x == f[x]) return x;
  return f[x] = find(f[x]);
}
struct rd {
  int now, next, to;
} road[200010];
inline void addedge(int x, int y) {
  road[++tot].next = head[x];
  road[tot].to = y;
  road[tot].now = x;
  head[x] = tot;
}
inline void dfs(int x) {
  for (int now = head[x]; now; now = road[now].next)
    if (col[road[now].to] != 2) {
      if (col[road[now].to] == col[x]) {
        spe = x, root = x, bk[road[now].to] = now;
        return;
      }
    } else {
      col[road[now].to] = col[x] ^ 1;
      flag[now >> 1] = 1;
      bk[road[now].to] = now;
      dfs(road[now].to);
      if (spe) return;
    }
}
inline void dfs(int x, int fa) {
  for (int now = head[x]; now; now = road[now].next) {
    if (road[now].to != fa && flag[now >> 1] == 1) {
      dfs(road[now].to, x);
      a[now >> 1] = v[road[now].to] - w[road[now].to];
      w[x] += a[now >> 1];
    }
  }
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) f[i] = i;
  for (int i = 1; i <= n; i++) scanf("%d", &v[i]);
  for (int i = 1, x, y; i <= m; i++)
    scanf("%d%d", &x, &y), addedge(x, y), addedge(y, x);
  for (int i = 1; i <= n; i++) col[i] = 2;
  col[1] = 0;
  dfs(1);
  if (spe == 0) {
    long long V = 0;
    for (int i = 1; i <= n; i++)
      if (col[i] == 0)
        V += v[i];
      else
        V -= v[i];
    if (V != 0)
      printf("NO\n");
    else {
      printf("YES\n");
      dfs(1, 0);
      for (int i = 1; i <= m; i++) printf("%I64d\n", a[i]);
    }
    return 0;
  } else {
    printf("YES\n");
    dfs(root, 0);
    a[bk[root] >> 1] += (v[root] - w[root]) / 2;
    for (int i = road[bk[root]].now, j = -1; i != root;
         i = road[bk[i]].now, j *= -1)
      a[bk[i] >> 1] += j * (v[root] - w[root]) / 2;
    for (int i = 1; i <= m; i++) printf("%I64d\n", a[i]);
  }
  return 0;
}
