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;
template <class C>
void mini(C &a4, C b4) {
  a4 = min(a4, b4);
}
template <class C>
void maxi(C &a4, C b4) {
  a4 = max(a4, b4);
}
template <class TH>
void _dbg(const char *sdbg, TH h) {
  cerr << sdbg << '=' << h << endl;
}
template <class TH, class... TA>
void _dbg(const char *sdbg, TH h, TA... a) {
  while (*sdbg != ',') cerr << *sdbg++;
  cerr << '=' << h << ',';
  _dbg(sdbg + 1, a...);
}
template <class T>
ostream &operator<<(ostream &os, vector<T> V) {
  os << "[";
  for (auto vv : V) os << vv << ",";
  return os << "]";
}
template <class L, class R>
ostream &operator<<(ostream &os, pair<L, R> P) {
  return os << "(" << P.first << "," << P.second << ")";
}
const long long MAX = 1e5 + 10;
long long n, m;
long long c[MAX];
vector<pair<long long, long long> > d[MAX];
long long res[MAX];
long long s[MAX];
long long par[MAX];
long long pari[MAX];
pair<long long, long long> np = {-1, -1};
long long npi = -1;
bool vis[MAX];
void dfs(long long v, long long gl) {
  vis[v] = 1;
  s[v] = gl;
  for (pair<long long, long long> el : d[v]) {
    if (!vis[el.first]) {
      par[el.first] = v;
      pari[el.first] = el.second;
      dfs(el.first, gl + 1);
      res[el.second] += c[el.first];
      c[v] -= c[el.first];
    } else {
      if (s[v] % 2 == s[el.first] % 2) {
        np = {v, el.first};
        npi = el.second;
      }
    }
  }
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout << fixed << setprecision(11);
  if (0) cout << fixed << setprecision(6);
  cin >> n >> m;
  for (long long i = (0); i <= ((long long)(n)-1); i++) cin >> c[i];
  for (long long i = (0); i <= ((long long)(m)-1); i++) {
    res[i] = 1;
    long long a, b;
    cin >> a >> b;
    a--;
    b--;
    c[a]--;
    c[b]--;
    d[a].push_back({b, i});
    d[b].push_back({a, i});
  }
  dfs(0, 0);
  for (long long i = (0); i <= ((long long)(n)-1); i++) {
    if (0) cout << s[i] << " ";
  }
  if (0) cout << "\n";
  if (c[0] != 0) {
    (c[0]);
    for (long long i = (0); i <= ((long long)(m)-1); i++) {
      if (0) cout << res[i] << " ";
    }
    if (0) cout << "\n";
    if (np.first == -1) {
      cout << "NO\n";
      return 0;
    }
    long long zn = 1;
    long long il = c[0] / 2;
    if (s[np.first] % 2 == 1) {
      zn = -1;
    }
    (npi);
    res[npi] += zn * il;
    (res[npi], npi, np);
    for (long long ak : {np.first, np.second}) {
      (ak, il);
      long long x = zn * -1;
      while (ak != 0) {
        res[pari[ak]] += x * il;
        ak = par[ak];
        x *= -1;
      }
    }
  }
  cout << "YES\n";
  for (long long i = (0); i <= ((long long)(m)-1); i++) {
    cout << res[i] << "\n";
  }
}
