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;
struct half_edge {
  int v, cost;
};
const int mx = 300000;
int n, m, c[mx], p[mx], h[mx], used[mx];
vector<int> g[mx], t[mx], odd;
vector<half_edge> he;
bool dfs(int v, int hi, int pv) {
  p[v] = pv;
  h[v] = hi;
  used[v] = 1;
  for (auto en : g[v]) {
    int v1 = he[en].v;
    if (used[v1] == 1 && v1 != pv && h[v1] < h[v]) {
      if ((h[v1] - h[v]) % 2 == 0) {
        int u = v;
        while (u != v1) {
          odd.push_back(u);
          u = p[u];
        }
        odd.push_back(v1);
        return 1;
      }
    } else {
      if (used[v1] == 0) dfs(v1, hi + 1, v);
    }
  }
}
void build_st(int v, int enu) {
  if (enu != -1) t[v].push_back(enu);
  used[v] = 1;
  for (auto en : g[v]) {
    int v1 = he[en].v;
    if (used[v1] == 0) {
      t[v].push_back(en);
      build_st(v1, en ^ 1);
    }
  }
}
int put_cost(int v, bool root) {
  int top;
  if (!root)
    top = 1;
  else
    top = 0;
  for (int i = top; i < t[v].size(); ++i) {
    int v1 = he[t[v][i]].v;
    int res = put_cost(v1, 0);
    c[v] -= res;
    he[t[v][i]].cost = res;
  }
  if (!root) {
    he[t[v][0]].cost = c[v];
    int kek = c[v];
    c[v] = 0;
    return kek;
  } else {
    return c[v];
  }
}
void add_cost(int u, int v, int cost) {
  for (auto en : g[u]) {
    int v1 = he[en].v;
    if (v == v1) {
      he[en].cost += cost;
    }
  }
  for (auto en : g[v]) {
    int v1 = he[en].v;
    if (u == v1) {
      he[en].cost += cost;
    }
  }
  c[u] -= cost;
  c[v] -= cost;
}
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; ++i) {
    cin >> c[i];
  }
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    u--;
    v--;
    he.push_back({v, 0});
    he.push_back({u, 0});
    g[u].push_back(i * 2);
    g[v].push_back(i * 2 + 1);
  }
  dfs(0, 0, -1);
  if (odd.size() == 0) {
    for (int i = 0; i < n; ++i) {
      used[i] = 0;
    }
    build_st(0, -1);
    int res = put_cost(0, 1);
    if (res == 0) {
      cout << "YES" << endl;
      for (int i = 0; i < m; ++i) {
        cout << he[2 * i].cost << endl;
      }
    } else {
      cout << "NO" << endl;
    }
  } else {
    int root = odd[0];
    for (int i = 0; i < n; ++i) {
      used[i] = 0;
    }
    build_st(root, -1);
    int res = put_cost(root, 1);
    int sz = odd.size();
    for (int i = 0; i < sz - 1; ++i) {
      if (i % 2 == 0) {
        add_cost(odd[i], odd[i + 1], res / 2);
      } else {
        add_cost(odd[i], odd[i + 1], -res / 2);
      }
    }
    add_cost(odd[sz - 1], odd[0], res / 2);
    cout << "YES" << endl;
    for (int i = 0; i < m; ++i) {
      cout << he[2 * i].cost << endl;
    }
  }
}
