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 = 1 << 17;
int n, m;
vector<int> e[N];
int c[N];
int u1[N], u2[N];
int col[N];
long long ans[N];
long long a[N];
void dfs1(int v, int pr) {
  col[v] = 1;
  a[v] = 0;
  for (int id : e[v]) {
    if (id == pr) continue;
    int to = u1[id] ^ u2[id] ^ v;
    if (col[to] == 0) {
      dfs1(to, id);
      ans[id] = c[to] - a[to];
      a[to] += ans[id];
      a[v] += ans[id];
    } else if (col[to] == 1) {
      ans[id] = 0;
    } else {
      continue;
    }
  }
  col[v] = 2;
}
vector<int> cycle;
int col2[N];
int part[N];
vector<int> st;
void dfs2(int v, int pr, int cc) {
  col2[v] = 1;
  a[v] = 0;
  part[v] = cc;
  st.push_back(pr);
  for (int id : e[v]) {
    if (id == pr) continue;
    int to = u1[id] ^ u2[id] ^ v;
    if (col2[to] == 0) {
      dfs2(to, id, cc ^ 1);
    } else if (col2[to] == 1) {
      if (part[v] == part[to] && cycle.empty()) {
        cycle.push_back(id);
        for (int i = (int)st.size() - 1;; i--) {
          if (st[i] == -1) break;
          cycle.push_back(st[i]);
          if (u1[st[i]] == to || u2[st[i]] == to) break;
        }
      }
    } else {
      continue;
    }
  }
  st.pop_back();
  col2[v] = 2;
}
int main() {
  while (scanf("%d%d", &n, &m) == 2) {
    for (int i = 0; i < n; i++) {
      e[i].clear();
    }
    for (int i = 0; i < n; i++) scanf("%d", &c[i]);
    for (int i = 0; i < m; i++) {
      scanf("%d%d", &u1[i], &u2[i]);
      u1[i]--;
      u2[i]--;
      e[u1[i]].push_back(i);
      e[u2[i]].push_back(i);
    }
    for (int i = 0; i < n; i++) {
      col[i] = 0;
      col2[i] = 0;
      part[i] = -1;
    }
    bool ok = 1;
    for (int i = 0; i < n; i++) {
      if (col[i] != 0) continue;
      assert(i == 0);
      cycle.clear();
      dfs2(i, -1, 0);
      int v = i;
      if (!cycle.empty()) {
        v = u1[cycle[0]];
        assert(cycle.size() % 2 == 1);
        int iid = cycle.back();
        if (!(u1[iid] == v || u2[iid] == v)) {
          rotate(cycle.begin(), cycle.begin() + 1, cycle.end());
        }
      }
      dfs1(v, -1);
      if (a[v] != c[v]) {
        if (cycle.empty()) {
          ok = 0;
        } else {
          assert((a[v] - c[v]) % 2 == 0);
          long long o = (c[v] - a[v]) / 2;
          int iid = cycle.back();
          bool f = u1[iid] == v || u2[iid] == v;
          for (int j = 0; j < (int)cycle.size(); j++) {
            ans[cycle[j]] += o * ((j % 2) ? -1 : 1);
          }
        }
      }
    }
    if (ok) {
      vector<long long> d(n);
      for (int i = 0; i < m; i++) {
        d[u1[i]] += ans[i];
        d[u2[i]] += ans[i];
      }
      for (int i = 0; i < n; i++) {
        assert(d[i] == c[i]);
      }
      printf("YES\n");
      for (int i = 0; i < m; i++) printf("%lld\n", ans[i]);
    } else {
      printf("NO\n");
    }
  }
  return 0;
}
