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 S, class T>
ostream& operator<<(ostream& o, const pair<S, T>& p) {
  return o << "(" << p.first << "," << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& o, const vector<T>& vc) {
  o << "sz = " << vc.size() << endl << "[";
  for (const T& v : vc) o << v << ",";
  o << "]";
  return o;
}
using ll = long long;
int N, M;
const int MN = 100010;
vector<int> G[MN];
ll a[MN];
int d[MN];
bool vis[MN];
using P = pair<int, int>;
map<P, int> p2id;
bool spt[MN];
ll ans[MN];
void dfsd(int v = 0) {
  vis[v] = 1;
  for (int u : G[v]) {
    if (!vis[u]) {
      d[u] = d[v] + 1;
      spt[p2id[P(v, u)]] = 1;
      dfsd(u);
    }
  }
}
void dfs(int v = 0, int p = -1) {
  vis[v] = 1;
  for (int u : G[v]) {
    if (!vis[u]) {
      dfs(u, v);
      a[v] -= a[u];
    }
  }
  if (p != -1) {
    ans[p2id[P(v, p)]] = a[v];
  } else {
    assert(a[v] == 0);
  }
}
void answer() {
  puts("YES");
  for (int i = 0; i < (int)(M); i++) cout << ans[i] << endl;
  exit(0);
}
ll sm;
int main() {
  cin >> N >> M;
  for (int i = 0; i < (int)(N); i++) cin >> a[i];
  for (int i = 0; i < (int)(M); i++) {
    int x, y;
    cin >> x >> y;
    x--, y--;
    G[x].push_back(y);
    G[y].push_back(x);
    p2id[P(x, y)] = i;
    p2id[P(y, x)] = i;
  }
  dfsd();
  for (int i = 0; i < (int)(N); i++) {
    if (d[i] % 2 == 0)
      sm += a[i];
    else
      sm -= a[i];
  }
  if (sm == 0) {
    for (int i = 0; i < (int)(N); i++) vis[i] = 0;
    dfs();
    answer();
  } else {
    for (auto it : p2id) {
      P p = it.first;
      int i = it.second;
      if (spt[i]) continue;
      int x = p.first, y = p.second;
      if ((d[x] - d[y]) % 2 != 0) continue;
      if (d[x] % 2 == 1) sm = -sm;
      assert(sm % 2 == 0);
      ans[i] = sm / 2;
      a[x] -= sm / 2;
      a[y] -= sm / 2;
      for (int i = 0; i < (int)(N); i++) vis[i] = 0;
      dfs();
      answer();
    }
  }
  puts("NO");
}
