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 gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
const int MAXN = 100000;
const int MAXM = 100000;
int n, m;
int want[MAXN];
vector<pair<int, int> > adj[MAXN];
bool intree[MAXM];
int oddroot;
int col[MAXN];
void dfs(int at, int par) {
  col[at] = par == -1 ? 0 : 1 - col[par];
  for (int i = (0); i < (((int)(adj[at]).size())); ++i) {
    int to = adj[at][i].first;
    if (to == par) continue;
    if (col[to] == -1) {
      intree[adj[at][i].second] = true;
      dfs(to, at);
    } else {
      if (oddroot == -1 && col[to] == col[at]) oddroot = at;
    }
  }
}
int ans[MAXM];
int solve(int at, int parid) {
  int sum = 0;
  for (int i = (0); i < (((int)(adj[at]).size())); ++i) {
    int to = adj[at][i].first, id = adj[at][i].second;
    if (id == parid || !intree[id]) continue;
    int childsum = solve(to, id);
    ans[id] = want[to] - childsum;
    sum += ans[id];
  }
  return sum;
}
bool modify(int at, int parid, int by) {
  for (int i = (0); i < (((int)(adj[at]).size())); ++i) {
    int to = adj[at][i].first, id = adj[at][i].second;
    if (id == parid) continue;
    if (to == oddroot) {
      ans[id] += by;
      return true;
    }
    if (!intree[id]) continue;
    if (modify(to, id, -by)) {
      ans[id] += by;
      return true;
    }
  }
  return false;
}
void run() {
  scanf("%d%d", &n, &m);
  for (int i = (0); i < (n); ++i) scanf("%d", &want[i]);
  for (int i = (0); i < (m); ++i) {
    int a, b;
    scanf("%d%d", &a, &b);
    --a, --b;
    adj[a].push_back(make_pair(b, i));
    adj[b].push_back(make_pair(a, i));
    intree[i] = false;
  }
  memset(col, -1, sizeof(col));
  oddroot = -1;
  dfs(0, -1);
  int root = oddroot;
  if (root == -1) root = 0;
  memset(ans, 0, sizeof(ans));
  int childsum = solve(root, -1);
  int diff = want[root] - childsum;
  if (diff != 0 && oddroot != -1) {
    assert(diff % 2 == 0);
    assert(modify(root, -1, diff / 2));
    diff = 0;
  }
  if (diff != 0) {
    printf("NO\n");
    return;
  }
  for (int i = (0); i < (m); ++i) assert(abs(ans[i]) <= 2 * n * n);
  printf("YES\n");
  for (int i = (0); i < (m); ++i) printf("%d\n", ans[i]);
}
int main() {
  run();
  return 0;
}
