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 = 1e5 + 5;
const int M = N * 25;
int n, m;
long long C[M], x, y, tar[N], dep[N], in[M];
int fir[N], ne[M], to[M], cnt = 1, fa[N], fan[N];
void add(int x, int y) {
  ne[++cnt] = fir[x];
  fir[x] = cnt;
  to[cnt] = y;
}
void link(int x, int y) {
  add(x, y);
  add(y, x);
}
bool vis[N];
int dfs(int x, int f) {
  int res = 0;
  fa[x] = f;
  dep[x] = dep[f] + 1;
  vis[x] = 1;
  for (int i = fir[x]; i; i = ne[i]) {
    int V = to[i];
    if (vis[V]) {
      if (V != f) {
        if ((dep[V] + dep[x]) & 1)
          ;
        else
          res = i;
      }
      continue;
    }
    int cur = 0;
    if (cur = dfs(V, x)) res = cur;
    if (tar[V]) {
      tar[x] -= tar[V];
      C[i] += tar[V];
      C[i ^ 1] += tar[V];
      tar[V] = 0;
    }
    fan[V] = i;
  }
  return res;
}
void Bush(int x) {
  while (1) {
    if (!fa[x]) break;
    if (tar[x]) {
      tar[fa[x]] -= tar[x];
      C[fan[x]] += tar[x];
      C[fan[x] ^ 1] += tar[x];
      tar[x] = 0;
    }
    x = fa[x];
  }
}
int main(void) {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%lld", &tar[i]);
  for (int i = 1; i <= m; ++i) {
    scanf("%d%d", &x, &y);
    link(x, y);
  }
  for (int i = 1; i <= n; ++i) {
    if (!vis[i]) {
      int cur = dfs(i, 0);
      if ((abs(tar[i]) & 1) || (!cur && tar[i])) {
        return puts("NO") * 0;
      }
      if (dep[to[cur]] & 1) {
        C[cur] = C[cur ^ 1] += tar[i] / 2;
        tar[to[cur ^ 1]] = tar[to[cur]] = -tar[i] / 2;
      } else {
        C[cur] = C[cur ^ 1] -= tar[i] / 2;
        tar[to[cur ^ 1]] = tar[to[cur]] = tar[i] / 2;
      }
      Bush(to[cur]);
      Bush(to[cur ^ 1]);
    }
  }
  puts("YES");
  for (int i = 1; i <= m; ++i) printf("%lld\n", C[i * 2]);
}
