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 MAXN = 1E5 + 10;
int n, m, dep[MAXN], fa[MAXN], anc[MAXN], ance[MAXN], jmp[MAXN][19];
vector<pair<int, int> > g[MAXN];
vector<tuple<int, int, int> > es;
bool chk[MAXN];
long long Ans[MAXN], c[MAXN];
int find(int x) { return x == fa[x] ? x : x = find(fa[x]); }
void dfs(int x, int fa) {
  dep[x] = dep[fa] + 1;
  anc[x] = fa;
  jmp[x][0] = fa;
  for (auto e : g[x])
    if (e.first != fa)
      dfs(e.first, x), Ans[e.second] = c[e.first], c[x] -= c[e.first],
                       ance[e.first] = e.second;
}
int LCA(int x, int y) {
  if (dep[x] < dep[y]) swap(x, y);
  for (int j = 18; ~j; j--)
    if (dep[jmp[x][j]] >= dep[y]) x = jmp[x][j];
  if (x == y) return x;
  for (int j = 18; ~j; j--)
    if (jmp[x][j] != jmp[y][j]) x = jmp[x][j], y = jmp[y][j];
  return jmp[x][0];
}
int get_dis(int x, int y) { return dep[x] + dep[y] - 2 * dep[LCA(x, y)] + 1; }
void change_val(int x, int dlt) {
  int ff = -1;
  while (x) {
    Ans[ance[x]] += dlt * ff;
    ff *= -1;
    x = anc[x];
  }
}
void Output() {
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%lld\n", Ans[i]);
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%lld", &c[i]), fa[i] = i;
  for (int i = 1, u, v; i <= m; i++) {
    scanf("%d%d", &u, &v);
    int U = find(u), V = find(v);
    if (U != V) {
      chk[i] = 1;
      g[u].push_back({v, i});
      g[v].push_back({u, i});
      fa[U] = V;
    } else
      es.push_back(tuple<int, int, int>(u, v, i));
  }
  dfs(1, 0);
  if (c[1] == 0) return Output(), 0;
  if (c[1] & 1) return puts("NO"), 0;
  bool f = 0;
  for (auto e : es)
    if (get_dis(get<0>(e), get<1>(e)) & 1) {
      f = 1;
      Ans[get<2>(e)] = c[1] / 2;
      change_val(get<0>(e), c[1] / 2);
      change_val(get<1>(e), c[1] / 2);
      break;
    }
  if (f)
    Output();
  else
    puts("NO");
}
