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;
long long n, m, a[100069], sm[2], dg[100069], sq[100069];
pair<long long, long long> ed[100069];
vector<pair<long long, long long>> al[100069];
bitset<100069> vtd, dh, spc, ex;
queue<long long> q;
void dfs(long long x) {
  long long i, sz = al[x].size(), l, p;
  vtd[x] = 1;
  sm[dh[x]] += a[x];
  for (i = 0; i < sz; i++) {
    l = al[x][i].first;
    p = al[x][i].second;
    if (!vtd[l]) {
      dh[l] = !dh[x];
      dfs(l);
      ex[p] = 1;
    } else if (dh[l] == dh[x]) {
      spc[p] = 1;
    }
  }
}
int main() {
  long long i, k, l, p, sz;
  scanf("%lld%lld", &n, &m);
  for (i = 1; i <= n; i++) {
    scanf("%lld", a + i);
  }
  for (i = 1; i <= m; i++) {
    scanf("%lld%lld", &k, &l);
    ed[i] = {k, l};
    al[k].push_back({l, i});
    al[l].push_back({k, i});
  }
  dfs(1);
  for (i = 1; i <= m; i++) {
    k = ed[i].first;
    l = ed[i].second;
    if (spc[i]) {
      sq[i] = (sm[dh[k]] - sm[!dh[k]]) / 2;
      a[k] -= sq[i];
      a[l] -= sq[i];
      sm[dh[k]] = sm[!dh[k]];
    }
    dg[k] += ex[i];
    dg[l] += ex[i];
  }
  if (sm[0] != sm[1]) {
    printf("NO\n");
    return 0;
  }
  for (i = 1; i <= n; i++) {
    if (dg[i] == 1) {
      q.push(i);
    }
  }
  for (; !q.empty();) {
    k = q.front();
    q.pop();
    sz = al[k].size();
    for (i = 0; i < sz; i++) {
      l = al[k][i].first;
      p = al[k][i].second;
      if (ex[p]) {
        sq[p] = a[k];
        a[l] -= a[k];
        ex[p] = 0;
        dg[l]--;
        if (dg[l] == 1) {
          q.push(l);
        }
      }
    }
  }
  printf("YES\n");
  for (i = 1; i <= m; i++) {
    printf("%lld\n", sq[i]);
  }
}
