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;
int n, m;
const int Maxn = 100005;
struct Edge {
  int x, y;
  long long val;
  int wh(int p) { return (x == p) ? y : x; }
} Link[Maxn];
vector<int> E[Maxn];
int fa[Maxn];
int Findfa(int x) {
  if (fa[x] == x) return x;
  return fa[x] = Findfa(fa[x]);
}
int f[Maxn][20];
int deep[Maxn];
long long v[Maxn];
void Dfs(int x, int depth) {
  deep[x] = depth;
  for (int i = 0, s = E[x].size(); i < s; ++i) {
    int y = Link[E[x][i]].wh(x);
    if (y == f[x][0]) continue;
    f[y][0] = x;
    Dfs(y, depth + 1);
    Link[E[x][i]].val = v[y];
    v[x] -= v[y];
  }
}
int root;
int LCA(int x, int y) {
  if (deep[x] < deep[y]) swap(x, y);
  for (int i = 18; ~i; --i)
    if (deep[x] - (1 << i) >= deep[y]) x = f[x][i];
  if (x == y) return x;
  for (int i = 18; ~i; --i) {
    if (f[x][i] ^ f[y][i]) x = f[x][i], y = f[y][i];
  }
  return f[x][0];
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) fa[i] = i, scanf("%lld", &v[i]);
  for (int i = 1; i <= m; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    Link[i] = (Edge){x, y, 0};
    int f1 = Findfa(x), f2 = Findfa(y);
    if (f1 == f2) continue;
    fa[f1] = f2;
    E[x].push_back(i);
    E[y].push_back(i);
  }
  srand(time(0));
  root = rand() % n + 1;
  Dfs(root, 1);
  for (int i = 1; i <= 18; ++i)
    for (int x = 1; x <= n; ++x) f[x][i] = f[f[x][i - 1]][i - 1];
  if (abs(v[root]) & 1)
    puts("NO");
  else {
    bool flag = false;
    for (int i = 1; i <= m; ++i) {
      int x = Link[i].x, y = Link[i].y;
      if (f[x][0] == y || f[y][0] == x) continue;
      int lca = LCA(x, y);
      int size = deep[x] + deep[y] - 2 * deep[lca] + 1;
      if (size & 1) {
        int dlt = (deep[x] & 1) ? -1 : 1;
        dlt *= v[root] / 2;
        Link[i].val += dlt * -1;
        while (x != lca) {
          int p = f[x][0];
          for (int j = 0, s = E[p].size(); j < s; ++j) {
            if (Link[E[p][j]].wh(p) == x) {
              Link[E[p][j]].val += dlt;
              break;
            }
          }
          dlt *= -1;
          x = p;
        }
        dlt = (deep[y] & 1) ? -1 : 1;
        dlt *= v[root] / 2;
        while (y != lca) {
          int p = f[y][0];
          for (int j = 0, s = E[p].size(); j < s; ++j) {
            if (Link[E[p][j]].wh(p) == y) {
              Link[E[p][j]].val += dlt;
              break;
            }
          }
          dlt *= -1;
          y = p;
        }
        dlt *= 2;
        while (lca != root) {
          int p = f[lca][0];
          for (int j = 0, s = E[p].size(); j < s; ++j) {
            if (Link[E[p][j]].wh((p)) == lca) {
              Link[E[p][j]].val += dlt;
              break;
            }
          }
          dlt *= -1;
          lca = p;
        }
        flag = true;
        break;
      }
    }
    if (flag || v[root] == 0) {
      puts("YES");
      for (int i = 1; i <= m; ++i) printf("%lld\n", Link[i].val);
    } else
      puts("NO");
  }
  return 0;
}
