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 maxn = 3e5 + 14;
int n, m;
struct Edge {
  int v, u;
  long long w;
  int o(int x) { return x == v ? u : v; }
} e[maxn];
vector<Edge*> g[maxn];
vector<Edge*> cyc, cur;
Edge* par[maxn];
int col[maxn];
long long c[maxn];
int mark[maxn];
bool dfs(int v = 0, int c = 1) {
  col[v] = c;
  mark[v] = cur.size() + 1;
  for (auto e : g[v]) {
    int u = e->o(v);
    if (!col[u]) {
      par[u] = e;
      cur.push_back(e);
      if (dfs(u, 3 - c)) return 1;
      cur.pop_back();
    } else if (col[u] == c) {
      cyc.push_back(e);
      while (!mark[u]) cyc.push_back(par[u]), u = par[u]->o(u);
      while (u != v) {
        cyc.push_back(cur[mark[u] - 1]), u = cur[mark[u] - 1]->o(u);
      }
      return 1;
    }
  }
  mark[v] = 0;
  return 0;
}
void fix(int v, int p = -1) {
  mark[v] = 1;
  for (auto e : g[v]) {
    int u = e->o(v);
    if (!mark[u]) {
      fix(u, v);
      e->w = c[u];
      c[v] -= c[u];
    }
  }
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0);
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> c[i];
  for (int i = 0; i < m; i++) {
    cin >> e[i].v >> e[i].u;
    e[i].v--, e[i].u--;
    g[e[i].v].push_back(&e[i]);
    g[e[i].u].push_back(&e[i]);
  }
  int root = 0;
  bool hasCy = 0;
  if (dfs()) {
    root = -1;
    for (auto x : {cyc[0]->v, cyc[0]->u})
      for (auto y : {cyc.back()->v, cyc.back()->u})
        if (x == y) root = x;
    assert(root != -1);
    hasCy = 1;
  }
  memset(mark, 0, sizeof mark);
  fix(root);
  if (hasCy) {
    long long x = c[root] / 2;
    c[root] = 0;
    for (int i = 0; i < cyc.size(); i++) cyc[i]->w += (i & 1 ? -x : x);
  }
  if (!c[root]) {
    cout << "YES\n";
    for (int i = 0; i < m; i++) cout << e[i].w << '\n';
  } else
    cout << "NO\n";
}
