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 int N = 1e5 + 10;
struct edge {
  int u, v;
  int adj(int x) { return u + v - x; }
};
int n, c[N];
vector<int> adj[N];
vector<edge> e;
int lvl[N], pre[N], root;
vector<int> cycle;
void dfs1(int u) {
  for (auto ind : adj[u])
    if (ind != pre[u]) {
      auto ei = e[ind];
      int v = ei.adj(u);
      if (lvl[v]) {
        if ((lvl[u] + lvl[v]) % 2 == 0 && cycle.empty()) {
          for (int w = u; w != v; w = e[pre[w]].adj(w)) cycle.push_back(pre[w]);
          reverse((cycle).begin(), (cycle).end());
          cycle.push_back(ind);
          root = v;
        }
      } else {
        lvl[v] = lvl[u] + 1;
        pre[v] = ind;
        dfs1(v);
      }
    }
}
long long int ans[N];
bool vis[N];
long long int dfs2(int u, int pre) {
  if (vis[u]) return 0;
  vis[u] = 1;
  long long int sum = 0;
  for (auto ind : adj[u])
    if (ind != pre) {
      int v = e[ind].adj(u);
      sum += dfs2(v, ind);
    }
  if (pre != -1) ans[pre] = c[u] - sum;
  return c[u] - sum;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int m;
  cin >> n >> m;
  for (int i = 0; i < (int)(n); i++) cin >> c[i];
  e.resize(m);
  for (int i = 0; i < (int)(m); i++) {
    cin >> e[i].u >> e[i].v;
    e[i].u--;
    e[i].v--;
    adj[e[i].u].push_back(i);
    adj[e[i].v].push_back(i);
  }
  bool ok = 1;
  for (int u = 0; u < (int)(n); u++)
    if (!lvl[u]) {
      cycle.clear();
      lvl[u] = 1;
      pre[u] = -1;
      dfs1(u);
      if (cycle.empty()) {
        ok &= dfs2(u, -1) == 0;
      } else {
        auto delta = dfs2(root, -1) / 2;
        for (auto ind : cycle) {
          ans[ind] += delta;
          delta = -delta;
        }
      }
    }
  if (ok) {
    cout << "YES\n";
    for (int i = 0; i < (int)(m); i++) cout << ans[i] << '\n';
  } else
    cout << "NO\n";
  return 0;
}
