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;
long long c[100005];
pair<int, int> bruh[100005];
vector<int> e[100005];
int d[100005];
int p[100005];
vector<int> cyc;
void gc(int bt, int tp) {
  int mn = bt, mx = bt;
  int cur = bt;
  cyc.push_back(bt);
  while (cur != tp) {
    cur = p[cur];
    cyc.push_back(cur);
  }
}
bool dfs(int cn) {
  for (auto nn : e[cn]) {
    if (d[nn] == -1) {
      d[nn] = d[cn] + 1;
      p[nn] = cn;
      if (dfs(nn)) return true;
    } else if (nn != p[cn] && d[nn] < d[cn]) {
      if ((d[nn] - d[cn]) % 2 == 0) {
        gc(cn, nn);
        return true;
      }
    }
  }
  return false;
}
map<pair<int, int>, long long> res;
void ae(int u, int v, long long ch) {
  if (u > v) swap(u, v);
  res[{u, v}] += ch;
  c[u] += ch;
  c[v] += ch;
}
bool vis[100005];
void dfs2(int cn, int p) {
  vis[cn] = true;
  for (auto nn : e[cn]) {
    if (vis[nn]) continue;
    dfs2(nn, cn);
  }
  if (p != 0) {
    ae(cn, p, -c[cn]);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> m;
  for (int i = (1); i <= (signed)(n); i++) {
    int x;
    cin >> x;
    c[i] = -x;
  }
  for (int i = 0; i < (signed)(m); i++) {
    int u, v;
    cin >> u >> v;
    if (u > v) swap(u, v);
    e[u].push_back(v);
    e[v].push_back(u);
    bruh[i] = {u, v};
  }
  memset(d, -1, sizeof d);
  d[1] = 0;
  bool hmm = dfs(1);
  int rt;
  if (hmm) {
    rt = cyc[0];
  } else {
    rt = 1;
  }
  dfs2(rt, 0);
  if (!hmm) {
    if (c[rt] != 0) {
      cout << "NO\n";
    } else {
      cout << "YES\n";
      for (int i = 0; i < (signed)(m); i++) {
        cout << res[bruh[i]] << "\n";
      }
    }
  } else {
    long long d = -c[rt] / 2;
    for (int i = 0; i < (signed)(cyc.size() - 1); i++) {
      ae(cyc[i], cyc[i + 1], d);
      d = -d;
    }
    ae(cyc[0], cyc[cyc.size() - 1], d);
    cout << "YES\n";
    for (int i = 0; i < (signed)(m); i++) {
      cout << res[bruh[i]] << "\n";
    }
  }
  return 0;
}
