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;
int m;
bool vis[100002];
vector<int> v[100002];
long long int c[100002];
int dep[100002];
vector<pair<int, int> > V;
vector<int> g[100002];
long long int sum[2];
inline void dfs(int b, int pr = -1, int d = 0) {
  sum[d % 2] += c[b];
  dep[b] = d;
  vis[b] = true;
  for (int go : v[b]) {
    if (go == pr) continue;
    if (vis[go]) {
      if ((dep[b] - dep[go]) % 2 == 0) {
        V.push_back(make_pair(b, go));
      }
      continue;
    }
    g[b].push_back(go);
    dfs(go, b, d + 1);
  }
}
map<pair<int, int>, int> ids;
map<pair<int, int>, long long int> mp;
inline long long int dfs2(int b, int pr = -1) {
  if (g[b].size() == 0) {
    mp[make_pair(pr, b)] = c[b];
    return c[b];
  }
  long long int ret = 0;
  for (int go : g[b]) {
    ret += dfs2(go, b);
  }
  long long int need = c[b] - ret;
  if (need) {
    mp[make_pair(pr, b)] = need;
  }
  return need;
}
long long int ans[100002];
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    scanf("%lld", &c[i]);
  }
  for (int i = 0; i < m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    a--;
    b--;
    v[a].push_back(b);
    v[b].push_back(a);
    ids[make_pair(a, b)] = i;
    ids[make_pair(b, a)] = i;
  }
  dfs(0);
  if (sum[0] != sum[1] && V.size() == 0) {
    puts("NO");
    return 0;
  }
  long long int weigh = sum[0] - sum[1];
  while (weigh != 0) {
    if (V.size() == 0) {
      puts("NO");
      return 0;
    }
    int a = V.back().first;
    int b = V.back().second;
    V.pop_back();
    long long int add = 0;
    if (dep[a] & 1) {
      add += weigh / 2;
      sum[1] += add * 2;
    } else {
      add += weigh / 2;
      add = -add;
      sum[0] += add * 2;
    }
    c[a] += add;
    c[b] += add;
    mp[make_pair(a, b)] = -add;
    weigh = sum[0] - sum[1];
  }
  dfs2(0);
  for (auto it : mp) {
    ans[ids[it.first]] = it.second;
  }
  puts("YES");
  for (int i = 0; i < m; i++) {
    printf("%lld\n", ans[i]);
  }
  return 0;
}
