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>
#pragma GCC optimize("O2")
using namespace std;
const int MAXN = 1e5 + 10;
const long long MOD = 1e9 + 7;
const long long MOD2 = 998244353;
const long long INF = 8e18;
const int LOG = 20;
long long pw(long long a, long long b, long long mod) {
  return (!b ? 1
             : (b & 1 ? (a * pw(a * a % mod, b / 2, mod)) % mod
                      : pw(a * a % mod, b / 2, mod)));
}
vector<pair<long long, long long> > G[MAXN];
long long c[MAXN], H[MAXN], mark[MAXN], c2[MAXN], Ans[MAXN];
pair<long long, long long> E[MAXN], P;
long long sum[2];
void DFS(int v, int par = 0) {
  sum[H[v] % 2] += c[v];
  mark[v] = 1;
  for (auto y : G[v]) {
    int u = y.first, id = y.second;
    if (u == par) continue;
    if (!mark[u]) {
      H[u] = H[v] + 1;
      DFS(u, v);
      Ans[id] = c2[u];
      c2[v] -= Ans[id];
      c2[u] = 0;
    } else if (H[v] % 2 == H[u] % 2) {
      P = make_pair((1ll) * (H[v] % 2), id);
    }
  }
}
void dfs(int v) {
  mark[v] = 1;
  for (auto y : G[v]) {
    int u = y.first, id = y.second;
    if (!mark[u]) {
      dfs(u);
      Ans[id] = c[u];
      c[v] -= Ans[id];
      c[u] = 0;
    }
  }
  return;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> c[i];
    c2[i] = c[i];
  }
  for (int i = 1; i <= m; i++) {
    cin >> E[i].first >> E[i].second;
    G[E[i].first].push_back(make_pair(E[i].second, i));
    G[E[i].second].push_back(make_pair(E[i].first, i));
  }
  sum[0] = sum[1] = 0;
  P = make_pair(0ll, 0ll);
  DFS(1, 0);
  if (P == make_pair(0ll, 0ll)) {
    for (int i = 1; i <= n; i++) {
      if (c2[i] != 0 || sum[0] != sum[1]) return cout << "NO", 0;
    }
    cout << "YES"
         << "\n";
    for (int i = 1; i <= m; i++) {
      cout << Ans[i] << "\n";
    }
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    mark[i] = 0;
  }
  int id = P.second, way = P.first;
  if (sum[0] % 2 != sum[1] % 2) {
    return cout << "NO", 0;
  }
  if (way == 1) {
    Ans[id] = (sum[1] - sum[0]) / 2;
    c[E[id].first] -= Ans[id];
    c[E[id].second] -= Ans[id];
  } else {
    Ans[id] = (sum[0] - sum[1]) / 2;
    c[E[id].first] -= Ans[id];
    c[E[id].second] -= Ans[id];
  }
  dfs(1);
  cout << "YES"
       << "\n";
  for (int i = 1; i <= m; i++) {
    cout << Ans[i] << "\n";
  }
  return 0;
}
