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 <class T, class U>
void Min(T &a, U b) {
  if (a > b) a = b;
}
template <class T, class U>
void Max(T &a, U b) {
  if (a < b) a = b;
}
vector<pair<int, int> > g[100010];
int is[100010], c[100010], d[100010], co[100010];
pair<int, int> p[100010];
long long w[100010], cur[100010];
int s = -1, t, end_edge;
void dfs(int u, int fa = -1) {
  is[u] = 1;
  for (auto &o : g[u]) {
    if (o.second == fa) continue;
    int v = o.first;
    if (!is[v]) {
      d[v] = d[u] + 1;
      p[v] = {u, o.second};
      co[v] = co[u] ^ 1;
      dfs(v, o.second);
      w[o.second] = cur[v];
      cur[u] -= cur[v];
    } else if (d[v] < d[u] && co[v] == co[u] && s == -1) {
      s = u, t = v, end_edge = o.second;
    }
  }
}
void go(int u, int fa = -1) {
  is[u] = 1;
  for (auto &o : g[u]) {
    if (o.second == fa) continue;
    int v = o.first;
    if (!is[v] && o.second != end_edge) {
      go(v, o.second);
      w[o.second] = cur[v];
      cur[u] -= cur[v];
    }
  }
}
int main() {
  int n, m, j, k, i;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%d", &c[i]);
  for (int i = 0; i < m; i++) {
    scanf("%d%d", &j, &k);
    j--, k--;
    g[j].push_back({k, i}), g[k].push_back({j, i});
  }
  for (int i = 0; i < n; i++) cur[i] = c[i], is[i] = 0;
  dfs(0);
  if (!cur[0]) {
    puts("YES");
    for (int i = 0; i < m; i++) printf("%I64d\n", w[i]);
    return 0;
  }
  if (s == -1) {
    puts("NO");
    return 0;
  }
  for (int i = 0; i < n; i++) cur[i] = c[i], is[i] = 0;
  go(s);
  int first = s;
  k = 1;
  long long v = cur[s] / 2;
  while (first != t) {
    w[p[first].second] += v * k;
    k *= -1;
    first = p[first].first;
  }
  w[end_edge] = v * k;
  puts("YES");
  for (int i = 0; i < m; i++) printf("%I64d\n", w[i]);
  return 0;
}
