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;
template <typename T>
inline void upmin(T &x, T y) {
  y < x ? x = y : 0;
}
template <typename T>
inline void upmax(T &x, T y) {
  x < y ? x = y : 0;
}
const long double pi = acos(-1);
const int oo = 1 << 30;
const long long OO = 1e18;
const int N = 1e5 + 100;
int gi() {
  int w = 0;
  bool q = 1;
  char c = getchar();
  while ((c < '0' || c > '9') && c != '-') c = getchar();
  if (c == '-') q = 0, c = getchar();
  while (c >= '0' && c <= '9') w = w * 10 + c - '0', c = getchar();
  return q ? w : -w;
}
int head[N], nxt[N * 2], to[N * 2];
int u[N], v[N], dis[N];
int fa[N], e[N];
inline int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }
long long ans[N], c[N];
inline void dfs(int k, int fa) {
  for (int i = head[k]; i; i = nxt[i])
    if (to[i] != fa) dis[to[i]] = dis[k] ^ 1, dfs(to[i], k);
}
inline void solve(int k) {
  for (int i = head[k]; i; i = nxt[i])
    if (to[i] != fa[k]) {
      fa[to[i]] = k, e[to[i]] = i >> 1;
      solve(to[i]);
      c[k] -= ans[i >> 1] = c[to[i]];
    }
}
int main() {
  int n = gi(), m = gi(), i, a, b, t;
  for (i = 1; i <= n; i++) c[i] = gi(), fa[i] = i;
  for (i = 1; i <= m; i++)
    if (find(a = gi()) == find(b = gi()))
      u[i] = a, v[i] = b;
    else {
      to[i * 2] = a, nxt[i * 2] = head[b], head[b] = i * 2;
      to[i * 2 | 1] = b, nxt[i * 2 | 1] = head[a], head[a] = i * 2 | 1;
      fa[fa[a]] = b;
    }
  memset(fa, 0, sizeof(fa));
  dfs(1, 0);
  for (i = 1; i <= m; i++)
    if (u[i] && dis[u[i]] == dis[v[i]]) {
      solve(u[i]);
      ans[i] = t = c[u[i]] / 2;
      for (a = v[i]; a != u[i]; a = fa[a]) t = -t, ans[e[a]] += t;
      goto out;
    }
  solve(1);
  if (c[1]) return puts("NO"), 0;
out:;
  puts("YES");
  for (i = 1; i <= m; i++) printf("%I64d\n", ans[i]);
  return 0;
}
