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;
vector<pair<long long, long long> > vec[100002];
tuple<long long, long long> tp[100002];
vector<long long> vt;
long long n, m;
long long cl[100002], edg = -1, te = 0, sum[3], ans[100002];
long long bip(long long x, long long y) {
  cl[x] = y;
  sum[y] += vt[x];
  for (long long i = 0; i < vec[x].size(); ++i) {
    long long u = vec[x][i].first;
    long long v = vec[x][i].second;
    if (cl[u]) {
      if (cl[u] == cl[x]) edg = v, te = cl[u];
      continue;
    }
    bip(u, 3 - y);
  }
  return 0;
}
long long DFS(long long x, long long y, long long z) {
  cl[x] = 1;
  for (long long i = 0; i < vec[x].size(); ++i) {
    long long u = vec[x][i].first;
    long long v = vec[x][i].second;
    if (!cl[u]) DFS(u, v, x);
  }
  if (x != 0) vt[z] -= vt[x], ans[y] = vt[x];
  return 0;
}
int main() {
  memset(cl, 0, sizeof(cl)), memset(sum, 0, sizeof(sum)),
      memset(ans, 0, sizeof(ans));
  cin >> n >> m;
  for (long long i = 0; i < n; ++i) {
    long long x;
    cin >> x;
    vt.push_back(x);
  }
  for (long long i = 0; i < m; ++i) {
    long long x, y;
    cin >> x >> y;
    x--, y--, vec[x].push_back(make_pair(y, i)),
        vec[y].push_back(make_pair(x, i));
    tp[i] = make_tuple(x, y);
  }
  bip(0, 1);
  if (edg == -1 && sum[1] != sum[2]) {
    cout << "NO";
    return 0;
  }
  if (edg != -1) {
    long long cur = sum[te] - sum[3 - te];
    if (cur & 1) {
      cout << "NO";
      return 0;
    }
    ans[edg] = cur / 2;
    long long x = get<0>(tp[edg]);
    long long y = get<1>(tp[edg]);
    vt[x] -= cur / 2, vt[y] -= cur / 2;
  }
  memset(cl, 0, sizeof(cl));
  DFS(0, 0, 0);
  cout << "YES" << endl;
  for (long long i = 0; i < m; ++i) cout << ans[i] << endl;
}
