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;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
long long Ans[100000 + 5], c[100000 + 5];
int n, m, head[100000 + 5], cnt = 1, vis[100000 + 5], C[100000 + 5], num = 0;
int Fa[100000 + 5], q[100000 + 5], top = 0, col[100000 + 5], inq[100000 + 5],
                                   from;
struct edge {
  int to, next;
} e[100000 * 2 + 5];
inline void ins(int f, int t) {
  e[++cnt] = (edge){t, head[f]};
  head[f] = cnt;
  e[++cnt] = (edge){f, head[t]};
  head[t] = cnt;
}
void dfs(int x, int fa) {
  vis[x] = 1;
  for (int i = head[x]; i; i = e[i].next)
    if (!vis[e[i].to])
      dfs(e[i].to, x), Ans[i >> 1] = c[e[i].to], c[x] -= c[e[i].to],
                                c[e[i].to] = 0;
}
void Find(int x, int fa) {
  vis[x] = 1;
  q[++top] = x;
  inq[x] = top;
  Fa[x] = fa;
  for (int i = head[x]; i && !num; i = e[i].next)
    if (e[i].to != fa) {
      if (vis[e[i].to]) {
        if (col[x] ^ col[e[i].to]) continue;
        int t;
        from = x;
        for (t = e[i].to; !inq[t]; t = Fa[t]) C[++num] = t;
        for (int j = inq[t]; j <= top; ++j) C[++num] = q[j];
      } else
        col[e[i].to] = col[x] ^ 1, Find(e[i].to, x);
    }
  --top;
  inq[x] = 0;
}
int E(int x, int y) {
  for (int i = head[x]; i; i = e[i].next)
    if (e[i].to == y) return i >> 1;
}
int main() {
  n = read();
  m = read();
  for (int i = 1; i <= n; ++i) c[i] = read();
  for (int i = 1; i <= m; ++i) ins(read(), read());
  Find(1, 0);
  memset(vis, 0, sizeof(vis));
  int rt = from ? from : 1;
  dfs(rt, 0);
  if (c[rt] && !from) return 0 * puts("NO");
  if (c[rt]) {
    long long s = c[rt] >> 1;
    for (int i = 1; i <= num; ++i)
      Ans[E(C[i], C[i % num + 1])] += (i == num ? 1 : ((i & 1) ? -1 : 1)) * s;
  }
  puts("YES");
  for (int i = 1; i <= m; ++i) printf("%lld\n", Ans[i]);
  return 0;
}
