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 p[411111];
vector<pair<int, int> > v[411111];
int n, m;
int x[411111], y[411111], d[411111];
int no[411111];
long long ans[411111];
long long c[411111];
long long cur[411111];
int get(int x) {
  if (p[x] == x) return x;
  return p[x] = get(p[x]);
}
void go(int x, int pr, int dd) {
  d[x] = dd;
  for (pair<int, int> to : v[x])
    if (to.first != pr) {
      go(to.first, x, dd + 1);
    }
}
void sol(int x, int pr) {
  for (pair<int, int> to : v[x])
    if (to.first != pr) {
      sol(to.first, x);
      ans[to.second] = c[to.first] - cur[to.first];
      cur[to.first] += ans[to.second];
      cur[x] += ans[to.second];
    }
}
int main() {
  ios::sync_with_stdio(false);
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> c[i];
  for (int i = 0; i < m; i++) {
    cin >> x[i] >> y[i];
    x[i]--;
    y[i]--;
  }
  for (int i = 0; i < n; i++) p[i] = i;
  for (int i = 0; i < m; i++) {
    if (get(x[i]) == get(y[i])) {
      no[i] = 1;
      continue;
    }
    v[x[i]].push_back(make_pair(y[i], i));
    v[y[i]].push_back(make_pair(x[i], i));
    p[get(x[i])] = get(y[i]);
  }
  go(0, 0, 1);
  int cen = 0;
  int ed = -1;
  for (int i = 0; i < m; i++)
    if (no[i]) {
      if (d[x[i]] % 2 != d[y[i]] % 2) {
        ans[i] = 0;
        continue;
      }
      cen = x[i];
      ed = i;
      break;
    }
  sol(cen, cen);
  if (c[cen] != cur[cen] && ed == -1) {
    cout << "NO" << endl;
    return 0;
  }
  if (c[cen] == cur[cen]) {
    cout << "YES" << endl;
    for (int i = 0; i < m; i++) cout << ans[i] << endl;
    return 0;
  }
  long long need = c[cen] - cur[cen];
  for (int i = 0; i < n; i++) cur[i] = 0;
  ans[ed] = need / 2;
  cur[x[ed]] += ans[ed];
  cur[y[ed]] += ans[ed];
  sol(cen, cen);
  cout << "YES" << endl;
  for (int i = 0; i < m; i++) cout << ans[i] << endl;
  return 0;
}
