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;
using INT = long long;
using VI = vector<int>;
using pii = pair<int, int>;
template <typename A, typename B>
inline void smin(A &a, const B &b) {
  if (a > b) a = b;
}
template <typename A, typename B>
inline void smax(A &a, const B &b) {
  if (a < b) a = b;
}
INT w[100100];
int val[100100], flag[100100], m, n;
vector<pii> adj[100100];
vector<int> cycle, tmp[100100];
int U, V;
int dfs(int u, int fa = 0) {
  flag[u] = flag[fa] ^ 1;
  for (auto p : adj[u]) {
    int v = p.first;
    if (v == fa) continue;
    if (~flag[v]) {
      if (flag[u] == flag[v]) {
        U = u, V = v;
        return 1;
      }
      continue;
    }
    tmp[u].push_back(v);
    tmp[v].push_back(u);
    if (flag[v] == -1) {
      if (dfs(v, u)) return 1;
    }
  }
  return 0;
}
int vst[100100];
map<pii, int> mp;
INT DFS(int u) {
  vst[u] = 1;
  INT tmp = 0;
  for (auto p : adj[u]) {
    int v = p.first, id = p.second;
    if (vst[v]) continue;
    w[id] = val[v] - DFS(v);
    tmp += w[id];
  }
  return tmp;
}
int rdfs(int u, int fa = 0) {
  for (int v : tmp[u]) {
    if (v == fa) continue;
    if (v == V) {
      cycle.push_back(mp[pii(u, v)]);
      return 1;
    }
    if (rdfs(v, u)) {
      cycle.push_back(mp[pii(u, v)]);
      return 1;
    }
  }
  return 0;
}
void odd_solve() {
  rdfs(U);
  memset(vst, 0, sizeof vst);
  INT first = val[U] - DFS(U);
  if (first & 1) {
    puts("NO");
    exit(0);
  }
  first /= 2;
  for (int i = 0; i < cycle.size(); i++) {
    if (i & 1)
      w[cycle[i]] += first;
    else
      w[cycle[i]] -= first;
  }
  w[mp[pii(U, V)]] += first;
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%I64d\n", w[i]);
  exit(0);
}
void solve() {
  if (val[1] != DFS(1)) {
    puts("NO");
    exit(0);
  }
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%I64d\n", w[i]);
  exit(0);
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) scanf("%d", &val[i]);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d %d", &u, &v);
    adj[u].push_back(pii(v, i));
    adj[v].push_back(pii(u, i));
    mp[pii(u, v)] = i;
    mp[pii(v, u)] = i;
  }
  memset(flag, -1, sizeof flag);
  flag[0] = 0;
  for (int i = 1; i <= n; i++) {
    if (~flag[i]) continue;
    if (dfs(i)) odd_solve();
  }
  solve();
  return 0;
}
