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>
bool uin(T &a, T b) {
  return a > b ? (a = b, true) : false;
}
template <class T>
bool uax(T &a, T b) {
  return a < b ? (a = b, true) : false;
}
const int maxn = 110000;
long long c[maxn], rc[maxn];
long long ec[maxn];
int h[maxn], vis[maxn];
pair<int, int> par[maxn];
vector<pair<int, int> > e[maxn];
void dfs(int v, int p) {
  vis[v] = 1;
  for (auto [u, id] : e[v]) {
    if (u == p) continue;
    if (vis[u]) continue;
    h[u] = h[v] + 1;
    par[u] = {v, id};
    dfs(u, v);
    long long delta = c[u] - rc[u];
    ec[id] = delta;
    rc[u] += delta;
    rc[v] += delta;
  }
}
void pathflip(int v, long long x) {
  while (v) {
    auto [u, id] = par[v];
    ec[id] += x;
    rc[v] += x;
    rc[u] += x;
    v = u;
    x = -x;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < (int)(n); ++i) cin >> c[i];
  for (int i = 0; i < (int)(m); ++i) {
    int u, v;
    cin >> u >> v;
    --u;
    --v;
    e[u].push_back({v, i});
    e[v].push_back({u, i});
  }
  dfs(0, -1);
  for (int v = 0; v < (int)(n); ++v)
    for (auto [u, id] : e[v]) {
      if (c[0] == rc[0]) break;
      if (h[v] < h[u]) continue;
      if (h[v] % 2 != h[u] % 2) continue;
      long long x = (c[0] - rc[0]) / 2 * (h[u] % 2 ? -1 : 1);
      ec[id] += x;
      rc[v] += x;
      rc[u] += x;
      pathflip(v, -x);
      pathflip(u, -x);
    }
  bool ok = true;
  for (int v = 0; v < (int)(n); ++v) {
    ok &= c[v] == rc[v];
  }
  if (ok) {
    cout << "YES\n";
    for (int i = 0; i < (int)(m); ++i) cout << ec[i] << '\n';
  } else
    cout << "NO\n";
  return 0;
}
