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 void File() {}
template <typename T>
inline void read(T &_) {
  _ = 0;
  T __ = getchar(), ___ = 1;
  while (!isdigit(__)) {
    if (__ == '-') ___ = -1;
    __ = getchar();
  }
  while (isdigit(__)) {
    _ = (_ << 1) + (_ << 3) + (__ ^ '0');
    __ = getchar();
  }
  _ *= ___;
}
template <typename T>
inline bool Chkmax(T &_, T __) {
  return _ < __ ? _ = __, 1 : 0;
}
template <typename T>
inline bool Chkmin(T &_, T __) {
  return _ > __ ? _ = __, 1 : 0;
}
const int N = 1e5 + 1e2;
int e = 1, n, m, clk;
bool vis[N];
int a[N], val[N], dep[N], beg[N], nex[N << 1], to[N << 1], St[N << 1][20],
    pos[N], Log[N << 1], f[N];
inline void add(int x, int y) { to[++e] = y, nex[e] = beg[x], beg[x] = e; }
inline int MIN(int x, int y) { return dep[y] > dep[x] ? x : y; }
inline void Init() {
  for (int i = 2; i <= clk; i++) Log[i] = Log[i >> 1] + 1;
  for (int i = 1; (1 << i) <= clk; i++)
    for (int j = 1; j + (1 << i) - 1 <= n; j++)
      St[j][i] = MIN(St[j][i - 1], St[j + (1 << (i - 1))][i - 1]);
}
inline int LCA(int x, int y) {
  int l = pos[x], r = pos[y];
  if (l > r) swap(l, r);
  int t = Log[r - l + 1];
  return MIN(St[l][t], St[r - (1 << t) + 1][t]);
}
inline int dis(int x, int y) { return dep[x] + dep[y] - 2 * dep[LCA(x, y)]; }
struct Edge {
  int u, v;
} E[N];
inline int Get_tree(int x, int fa, int Ed) {
  vis[x] = 1;
  dep[x] = dep[fa] + 1;
  St[pos[x] = ++clk][0] = x;
  f[x] = fa;
  for (int i = beg[x]; i; i = nex[i]) {
    if (!vis[to[i]]) a[x] -= Get_tree(to[i], x, i), St[++clk][0] = x;
  }
  val[Ed >> 1] = a[x];
  return a[x];
}
inline void Print() {
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%d\n", val[i]);
}
int cnt;
int Even[N];
inline void Jump(int x, int Goal, int tp) {
  while (x != Goal) {
    for (int i = beg[f[x]]; i; i = nex[i])
      if (to[i] == x) {
        val[i >> 1] += tp;
        tp = -tp;
        x = f[x];
        break;
      }
  }
}
int main() {
  File();
  read(n), read(m);
  for (int i = 1; i <= n; i++) read(a[i]);
  for (int i = 1, u, v; i <= m; i++)
    read(u), read(v), add(u, v), add(v, u), E[i] = (Edge){u, v};
  Get_tree(1, 0, 0);
  if (!a[1]) return Print(), 0;
  if ((a[1] & 1) != 0) return puts("NO");
  for (int i = 1; i <= m; i++) {
    if (!val[i]) {
      if (!((dis(E[i].u, E[i].v) + 1) & 1)) continue;
      Even[++cnt] = i;
    }
  }
  if (!cnt) return puts("NO"), 0;
  int u = E[Even[cnt]].u, v = E[Even[cnt]].v, lca = LCA(u, v);
  val[Even[cnt]] = ((dep[lca] & 1) == 0) ? -a[1] / 2 : a[1] / 2;
  Jump(u, lca, -val[Even[cnt]]), Jump(v, lca, -val[Even[cnt]]);
  Jump(lca, 1, -val[Even[cnt]] * 2);
  Print();
  return 0;
}
