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 mod = 1000000007LL;
long long large = 2000000000000000000LL;
vector<vector<pair<int, int> > > adj, adj1;
vector<long long> c;
vector<long long> val;
vector<pair<int, int> > parent;
int n, m;
struct UnionFind {
  vector<int> p;
  UnionFind(int n) {
    p.assign(n, 0);
    for (int i = 0; i < n; i++) p[i] = i;
  }
  int findSet(int i) { return p[i] == i ? i : p[i] = findSet(p[i]); }
  bool isSameSet(int i, int j) { return findSet(i) == findSet(j); }
  void unionSet(int i, int j) {
    if (isSameSet(i, j)) return;
    p[findSet(i)] = findSet(j);
  }
};
void dfs(int u, int pa, int r) {
  parent[u] = pair<int, int>(pa, r);
  long long temp = c[u];
  for (int j = 0; j < (int)adj1[u].size(); j++) {
    int v = adj1[u][j].first;
    int d = adj1[u][j].second;
    if (v != pa) {
      dfs(v, u, d);
      temp -= val[d];
    }
  }
  if (r != -1) val[r] = temp;
}
int main() {
  cin >> n >> m;
  adj.assign(n, vector<pair<int, int> >());
  adj1 = adj;
  c.assign(n, 0);
  val.assign(m, 0);
  parent.assign(n, pair<int, int>());
  for (int i = 0; i < n; i++) {
    cin >> c[i];
  }
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    x--;
    y--;
    adj[x].push_back(pair<int, int>(y, i));
    adj[y].push_back(pair<int, int>(x, i));
  }
  vector<int> dis(n, 1000000000);
  queue<int> q;
  dis[0] = 0;
  q.push(0);
  bool flag = true;
  int rt = -1;
  int other = -1;
  int tc = -1;
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    for (int j = 0; j < (int)adj[u].size(); j++) {
      int v = adj[u][j].first;
      if (dis[v] == 1000000000) {
        dis[v] = dis[u] + 1;
        q.push(v);
      } else {
        if (dis[v] == dis[u]) {
          flag = false;
          rt = u;
          other = v;
          tc = adj[u][j].second;
          break;
        }
      }
    }
    if (!flag) break;
  }
  if (flag) {
    long long temp = 0;
    for (int i = 0; i < n; i++) {
      if (dis[i] % 2)
        temp += c[i];
      else
        temp -= c[i];
    }
    if (temp != 0) {
      cout << "NO" << endl;
      return 0;
    }
    UnionFind uf(n);
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < (int)adj[i].size(); j++) {
        int v = adj[i][j].first;
        int d = adj[i][j].second;
        if (!uf.isSameSet(i, v)) {
          uf.unionSet(i, v);
          adj1[i].push_back(pair<int, int>(v, d));
          adj1[v].push_back(pair<int, int>(i, d));
        }
      }
    }
    dfs(0, -1, -1);
    cout << "YES" << endl;
    for (int i = 0; i < m; i++) cout << val[i] << endl;
    return 0;
  }
  UnionFind uf(n);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < (int)adj[i].size(); j++) {
      int v = adj[i][j].first;
      int d = adj[i][j].second;
      if (d != tc) {
        if (!uf.isSameSet(i, v)) {
          uf.unionSet(i, v);
          adj1[i].push_back(pair<int, int>(v, d));
          adj1[v].push_back(pair<int, int>(i, d));
        }
      }
    }
  }
  dfs(rt, -1, -1);
  long long temp = c[rt];
  for (int j = 0; j < (int)adj1[rt].size(); j++) {
    int d = adj1[rt][j].second;
    temp -= val[d];
  }
  temp /= 2;
  val[tc] = temp;
  while (other != rt) {
    int d = parent[other].second;
    val[d] -= temp;
    temp = -temp;
    other = parent[other].first;
  }
  cout << "YES" << endl;
  for (int i = 0; i < m; i++) {
    cout << val[i] << endl;
  }
  return 0;
}
