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;
vector<vector<pair<int, int> > > g;
vector<int> ans;
vector<int> c;
vector<bool> used;
vector<int> dp;
vector<int> col;
vector<int> p;
int val = 0;
int pos = 0;
int pos2 = 0;
void doit(int v) {
  used[v] = 1;
  for (auto i : g[v]) {
    if (!used[i.first]) {
      p[i.first] = v;
      doit(i.first);
      ans[i.second] = c[i.first] - dp[i.first];
      dp[i.first] += ans[i.second];
      dp[v] += ans[i.second];
    }
  }
}
bool dfs(int v) {
  used[v] = 1;
  for (auto i : g[v]) {
    if (!used[i.first]) {
      col[i.first] = col[v] ^ 1;
      if (dfs(i.first)) return 1;
    } else {
      if (col[i.first] != col[v] ^ 1) {
        val = i.second;
        pos = i.first;
        pos2 = v;
        return 1;
      }
    }
  }
  return 0;
}
int main() {
  iostream::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  int n, m;
  cin >> n >> m;
  ans.resize(m);
  g.resize(n);
  c.resize(n);
  dp.resize(n);
  p.resize(n);
  for (int i = 0; i < n; i++) cin >> c[i];
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    g[a].push_back({b, i});
    g[b].push_back({a, i});
  }
  used.assign(n, 0);
  doit(0);
  if (dp[0] == c[0]) {
    cout << "YES\n";
    for (int i : ans) cout << i << '\n';
    return 0;
  }
  used.assign(n, 0);
  col.resize(n);
  col[0] = 0;
  if (!dfs(0)) {
    cout << "NO";
    return 0;
  }
  cout << "YES\n";
  vector<int> to;
  int now = pos;
  while (now != 0) {
    to.push_back(now);
    now = p[now];
  }
  reverse(to.begin(), to.end());
  now = 0;
  for (int i = 0; i < to.size(); i++) {
    for (auto j : g[now]) {
      if (j.first == to[i]) {
        int up = c[now] - dp[now];
        ans[j.second] += up;
        dp[now] += up;
        dp[j.first] += up;
      }
    }
    now = to[i];
  }
  if ((c[pos] - dp[pos]) % 2 != 0) {
    return -1;
  }
  int up = (c[pos] - dp[pos]) / 2;
  ans[val] += up;
  dp[pos] += up;
  dp[pos2] += up;
  to.clear();
  now = pos2;
  while (now != pos) {
    to.push_back(now);
    now = p[now];
  }
  reverse(to.begin(), to.end());
  now = pos;
  for (int i = 0; i < to.size(); i++) {
    for (auto j : g[now]) {
      if (j.first == to[i]) {
        int up = c[now] - dp[now];
        ans[j.second] += up;
        dp[now] += up;
        dp[j.first] += up;
      }
    }
    now = to[i];
  }
  for (int i : ans) cout << i << '\n';
  return 0;
}
