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 comment(linker, "/STACK:1000000000")
using namespace std;
const int maxn = (int)1e5 + 10;
int ver = -1;
int num = -1;
long long c[maxn];
vector<pair<int, int> > ed[maxn];
long long res[maxn];
int h[maxn];
vector<pair<int, int> > e[maxn];
void dfs(int v, int d) {
  h[v] = d;
  for (int i = 0; i < (int)ed[v].size(); i++) {
    int u = ed[v][i].first;
    if (h[u] == -1) {
      e[v].push_back(make_pair(u, ed[v][i].second));
      e[u].push_back(make_pair(v, ed[v][i].second));
      dfs(u, d + 1);
    }
  }
}
bool used[maxn];
long long go(int v) {
  used[v] = true;
  long long ans = c[v];
  for (int i = 0; i < (int)e[v].size(); i++) {
    int u = e[v][i].first;
    int w = e[v][i].second;
    if (w == num) {
      continue;
    }
    if (!used[u]) {
      long long now = go(u);
      res[w] = now;
      ans -= now;
    }
  }
  return ans;
}
pair<int, int> edg[maxn];
int main() {
  memset(h, -1, sizeof h);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    scanf("%lld", &c[i]);
  }
  for (int i = 0; i < m; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    edg[i] = make_pair(a, b);
    ed[a].push_back(make_pair(b, i));
    ed[b].push_back(make_pair(a, i));
  }
  dfs(1, 0);
  for (int i = 0; i < m; i++) {
    int a = edg[i].first;
    int b = edg[i].second;
    int dst = abs(h[a] - h[b]);
    if (dst % 2 == 0) {
      ver = a;
      num = i;
      break;
    }
  }
  if (ver == -1) {
    ver = 1;
  }
  long long ch = go(ver);
  if (ch == 0) {
    cout << "YES" << endl;
    for (int i = 0; i < m; i++) {
      printf("%lld\n", res[i]);
    }
    return 0;
  }
  if (num == -1 || ch % 2 != 0) {
    cout << "NO" << endl;
    return 0;
  }
  res[num] = ch / 2;
  c[edg[num].first] -= ch / 2;
  c[edg[num].second] -= ch / 2;
  memset(used, 0, sizeof used);
  ch = go(ver);
  if (ch != 0) {
    throw 1;
  }
  cout << "YES" << endl;
  for (int i = 0; i < m; i++) {
    printf("%lld\n", res[i]);
  }
  return 0;
}
