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 maxn = 100011;
int pre[maxn << 1], son[maxn << 1], v[maxn << 1], now[maxn], tot;
void add(int a, int b, int c) {
  pre[++tot] = now[a];
  now[a] = tot;
  son[tot] = b;
  v[tot] = c;
}
void cc(int a, int b, int c) {
  add(a, b, c);
  add(b, a, c);
}
struct Te {
  int a, b;
  long long ans;
} e[maxn];
int n, m;
long long a[maxn];
void init() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%lld", a + i);
  for (int i = 1; i <= m; ++i) scanf("%d%d", &e[i].a, &e[i].b), e[i].ans = 0;
}
int fa[maxn], dep[maxn];
long long V[maxn];
inline int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }
void dfs(int x, int fa) {
  for (int p = now[x]; p; p = pre[p])
    if (son[p] != fa)
      V[son[p]] = a[son[p]], dep[son[p]] = dep[x] + 1, dfs(son[p], x),
      V[x] -= V[son[p]];
}
void work() {
  for (int i = 1; i <= n; ++i) fa[i] = i;
  for (int i = 1; i <= m; ++i) {
    if (find(e[i].a) != find(e[i].b)) {
      cc(e[i].a, e[i].b, i);
      fa[find(e[i].a)] = find(e[i].b);
    }
  }
  V[1] = a[1];
  dep[1] = 1;
  dfs(1, 0);
  if (V[1] & 1) return puts("NO"), void();
  bool ok = !V[1];
  if (!ok)
    for (int i = 1; i <= m; ++i)
      if ((dep[e[i].a] + dep[e[i].b]) % 2 == 0) {
        e[i].ans = ((dep[e[i].a] & 1) ? 1 : -1) * V[1] / 2;
        ok = 1;
        a[e[i].a] -= e[i].ans;
        a[e[i].b] -= e[i].ans;
        break;
      }
  if (!ok) return puts("NO"), void();
  V[1] = a[1];
  dfs(1, 0);
  for (int i = 1; i <= n; ++i)
    for (int p = now[i]; p; p = pre[p])
      if (dep[son[p]] > dep[i]) e[v[p]].ans = V[son[p]];
  puts("YES");
  for (int i = 1; i <= m; ++i) printf("%lld\n", e[i].ans);
}
int main() {
  init();
  work();
  return 0;
}
