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;
inline long long rd() {
  long long _x = 0;
  int _ch = getchar(), _f = 1;
  for (; !isdigit(_ch) && (_ch != '-') && (_ch != EOF); _ch = getchar())
    ;
  if (_ch == '-') {
    _f = 0;
    _ch = getchar();
  }
  for (; isdigit(_ch); _ch = getchar()) _x = _x * 10 + _ch - '0';
  return _f ? _x : -_x;
}
void write(long long _x) {
  if (_x >= 10)
    write(_x / 10), putchar(_x % 10 + '0');
  else
    putchar(_x + '0');
}
inline void wrt(long long _x, char _p) {
  if (_x < 0) putchar('-'), _x = -_x;
  write(_x);
  if (_p) putchar(_p);
}
int X[100005], Y[100005];
vector<pair<int, int> > G[100005];
int dep[100005];
bool vis[100005];
bool tag[100005];
int f[20][100005];
long long Ans[100005];
long long C[100005];
void dfs(int u, int fa) {
  vis[u] = 1;
  f[u][0] = fa;
  dep[u] = dep[fa] + 1;
  for (int i = int(1); i <= (int)(19); i++) f[u][i] = f[f[u][i - 1]][i - 1];
  for (auto i : G[u])
    if (!vis[i.first]) {
      tag[i.second] = 1;
      dfs(i.first, u);
      Ans[i.second] = C[i.first];
      C[u] -= Ans[i.second];
    }
}
int lca(int x, int y) {
  if (dep[x] < dep[y]) swap(x, y);
  for (int i = int(19); i >= (int)(0); i--)
    if (dep[f[x][i]] > dep[y]) x = f[x][i];
  if (x == y) return x;
  for (int i = int(19); i >= (int)(0); i--)
    if (f[x][i] != f[y][i]) x = f[x][i], y = f[y][i];
  return f[x][0];
}
int n, m;
int Tmp[100005];
int main() {
  n = rd(), m = rd();
  for (int i = int(1); i <= (int)(n); i++) C[i] = Tmp[i] = rd();
  for (int i = int(1); i <= (int)(m); i++) {
    X[i] = rd(), Y[i] = rd();
    G[X[i]].push_back(make_pair(Y[i], i));
    G[Y[i]].push_back(make_pair(X[i], i));
  }
  dfs(1, 0);
  if (abs(C[1]) % 2 != 0) {
    printf("NO\n");
    return 0;
  }
  for (int i = int(1); i <= (int)(m); i++)
    if (!tag[i]) {
      if ((dep[X[i]] + dep[Y[i]] - 2 * dep[lca(X[i], Y[i])]) % 2 != 0) continue;
      Ans[i] = C[1] / 2 * (dep[X[i]] % 2 == 0 ? -1 : 1);
      Tmp[X[i]] -= Ans[i], Tmp[Y[i]] -= Ans[i];
    }
  memset(tag, 0, sizeof tag), memset(vis, 0, sizeof vis);
  for (int i = int(1); i <= (int)(n); i++) C[i] = Tmp[i];
  dfs(1, 0);
  if (C[1] != 0) {
    printf("NO\n");
    return 0;
  }
  printf("YES\n");
  for (int i = int(1); i <= (int)(m); i++) wrt(Ans[i], '\n');
}
