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;
int n, m;
int c[100010];
int x[100010], y[100010];
vector<int> t[100010];
int f[100010];
int find(int x) { return (f[x] == -1 ? x : f[x] = find(f[x])); }
int fa[100010], dep[100010];
int dfn[100010], rnk[100010], totn = 0;
int siz[100010], son[100010], top[100010];
void dfs1(int k) {
  dep[k] = dep[fa[k]] + 1;
  siz[k] = 1;
  for (vector<int>::iterator it = t[k].begin(); it != t[k].end(); ++it) {
    if (*it == fa[k]) continue;
    fa[*it] = k;
    dfs1(*it);
    siz[k] += siz[*it];
    if (son[k] == 0 || siz[*it] > siz[son[k]]) son[k] = *it;
  }
  return;
}
void dfs2(int k, int tp) {
  dfn[k] = ++totn;
  rnk[totn] = k;
  top[k] = tp;
  if (son[k]) dfs2(son[k], tp);
  for (vector<int>::iterator it = t[k].begin(); it != t[k].end(); ++it) {
    if (*it == fa[k] || *it == son[k]) continue;
    dfs2(*it, *it);
  }
  return;
}
int LCA(int a, int b) {
  while (top[a] != top[b]) {
    if (dep[top[a]] < dep[top[b]]) swap(a, b);
    a = fa[top[a]];
  }
  return (dep[a] < dep[b] ? a : b);
}
long long v[100010];
void dfs3(int k) {
  v[k] = c[k];
  for (vector<int>::iterator it = t[k].begin(); it != t[k].end(); ++it) {
    if (*it == fa[k]) continue;
    dfs3(*it);
    v[k] -= v[*it];
  }
  return;
}
long long ve[100010];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%d", &c[i]);
  for (int i = 1; i <= m; ++i) scanf("%d%d", &x[i], &y[i]);
  memset(f, -1, sizeof(f));
  for (int i = 1; i <= m; ++i) {
    int p = find(x[i]), q = find(y[i]);
    if (p == q) continue;
    f[p] = q;
    t[x[i]].push_back(y[i]);
    t[y[i]].push_back(x[i]);
  }
  dfs1(1);
  dfs2(1, 1);
  dfs3(1);
  for (int i = 1; i <= m; ++i) {
    if (fa[x[i]] == y[i] || fa[y[i]] == x[i]) continue;
    if ((dep[x[i]] + dep[y[i]] - 2 * dep[LCA(x[i], y[i])]) % 2 == 0) {
      int val = v[1] / 2;
      val = val * (dep[x[i]] % 2 == 0 ? -1 : 1);
      ve[i] = val;
      c[x[i]] -= val;
      c[y[i]] -= val;
      break;
    }
  }
  dfs3(1);
  if (v[1] != 0) {
    puts("NO");
    return 0;
  }
  puts("YES");
  for (int i = 1; i <= m; ++i) {
    if (fa[x[i]] == y[i] || fa[y[i]] == x[i]) {
      if (dep[x[i]] < dep[y[i]]) swap(x[i], y[i]);
      ve[i] = v[x[i]];
    }
    printf("%lld\n", ve[i]);
  }
  return 0;
}
