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<vector<pair<long long, long long>>> graf;
vector<bool> was;
vector<long long> w;
vector<long long> res;
map<pair<long long, long long>, long long> e2i;
void Add(long long a, long long b, long long c) {
  w[a] += c;
  w[b] += c;
  res[e2i[{a, b}]] -= c;
}
void DFS(long long v) {
  if (was[v]) return;
  was[v] = true;
  for (int i = 0; i < ((long long)(graf[v]).size()); i++) {
    long long u = graf[v][i].first;
    DFS(u);
    Add(v, u, -w[u]);
  }
}
int main() {
  cin.sync_with_stdio(0);
  long long n, m;
  cin >> n >> m;
  was = vector<bool>(n, false);
  for (int i = 0; i < n; i++) {
    long long x;
    cin >> x;
    w.push_back(x);
  }
  graf = vector<vector<pair<long long, long long>>>(n);
  for (long long i = 0; i < m; i++) {
    long long a, b;
    cin >> a >> b;
    a--;
    b--;
    graf[a].push_back({b, i});
    graf[b].push_back({a, i});
    e2i[{a, b}] = i;
    e2i[{b, a}] = i;
  }
  queue<long long> q;
  q.push(0);
  vector<long long> mark(n, -1);
  mark[0] = 0;
  vector<long long> par(n, -1);
  deque<long long> cycle;
  long long sumB = 0, sumW = 0;
  while (((long long)(q).size()) > 0) {
    long long v = q.front();
    q.pop();
    for (long long i = 0; i < ((long long)(graf[v]).size()); i++) {
      long long u = graf[v][i].first;
      if (u == par[v]) continue;
      if (mark[u] != -1) {
        if (((long long)(cycle).size()) % 2 == 1) continue;
        long long a = v, b = u;
        if (mark[a] != mark[b]) {
          if (((long long)(cycle).size()) > 0) continue;
          b = par[b];
          cycle.clear();
          cycle.push_back(b);
        } else {
          cycle.clear();
        }
        while (a != b) {
          cycle.push_back(a);
          cycle.push_front(b);
          a = par[a];
          b = par[b];
        }
        cycle.push_back(a);
        break;
      } else if (mark[u] == -1) {
        mark[u] = (mark[v] + 1) % 2;
        q.push(u);
        par[u] = v;
      }
    }
    if (mark[v] == 0) {
      sumB += w[v];
    } else {
      sumW += w[v];
    }
  }
  res = vector<long long>(m, 1);
  for (long long i = 0; i < n; i++) w[i] -= ((long long)(graf[i]).size());
  if (((long long)(cycle).size()) == 0) {
    cycle.push_back(0);
    cycle.push_back(graf[0][0].first);
  }
  if (((long long)(cycle).size()) % 2 == 0) {
    if (sumB != sumW) {
      cout << "NO" << endl;
      return 0;
    }
    DFS(cycle[0]);
  } else {
    DFS(cycle[0]);
    if (w[cycle[0]] % 2 != 0) {
      cout << "NO" << endl;
      return 0;
    }
    Add(cycle[0], cycle[1], -w[cycle[0]] / 2);
    for (int i = 1; i < ((long long)(cycle).size()) - 1; i++) {
      Add(cycle[i], cycle[i + 1], -w[cycle[i]]);
    }
    Add(cycle[0], cycle.back(), -w[cycle[0]]);
  }
  cout << "YES" << endl;
  for (int i = 0; i < m; i++) {
    cout << res[i] << endl;
  }
  return 0;
}
