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;
const long double eps = 1e-9;
const int inf = (1 << 30) - 1;
const long long inf64 = ((long long)1 << 62) - 1;
const long double pi = acos(-1);
template <class T>
T sqr(T x) {
  return x * x;
}
template <class T>
T abs(T x) {
  return x < 0 ? -x : x;
}
int n, m;
vector<long long> x;
vector<vector<pair<int, int>>> adj;
vector<bool> in_tree;
vector<int> color;
vector<long long> res;
void DFSColor(int v) {
  for (int i = 0; i < ((int)(adj[v]).size()); ++i) {
    int u = adj[v][i].first;
    int num = adj[v][i].second;
    if (color[u] == -1) {
      color[u] = 1 - color[v];
      in_tree[num] = true;
      DFSColor(u);
    }
  }
}
long long DFSRes(int v, int p) {
  long long sum_cur = 0;
  for (int i = 0; i < ((int)(adj[v]).size()); ++i) {
    int u = adj[v][i].first;
    int num = adj[v][i].second;
    if (in_tree[num] && u != p) {
      long long cur = DFSRes(u, v);
      res[num] = cur;
      sum_cur += cur;
    }
  }
  return (x[v] - sum_cur);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> m;
  x.resize(n);
  for (int i = 0; i < n; ++i) {
    cin >> x[i];
  }
  adj.resize(n);
  for (int i = 0; i < m; ++i) {
    int v1, v2;
    cin >> v1 >> v2;
    --v1, --v2;
    adj[v1].push_back(make_pair(v2, i));
    adj[v2].push_back(make_pair(v1, i));
  }
  color.resize(n, -1);
  in_tree.resize(m, false);
  color[0] = 0;
  DFSColor(0);
  vector<long long> sum(2, 0);
  for (int i = 0; i < n; ++i) {
    sum[color[i]] += x[i];
  }
  res.resize(m, 0);
  bool key = false;
  for (int v = 0; v < n; ++v) {
    for (int i = 0; i < ((int)(adj[v]).size()); ++i) {
      int u = adj[v][i].first;
      if (color[u] == color[v]) {
        int num = adj[v][i].second;
        int c = color[v];
        long long d = (sum[c] - sum[1 - c]) / 2;
        res[num] = d;
        x[v] -= d;
        x[u] -= d;
        key = true;
        break;
      }
    }
    if (key) {
      break;
    }
  }
  if (!key && sum[0] != sum[1]) {
    cout << "NO"
         << "\n";
    return 0;
  }
  DFSRes(0, -1);
  cout << "YES"
       << "\n";
  for (int i = 0; i < m; ++i) {
    cout << res[i] << "\n";
  }
  return 0;
}
