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 + 5;
int N, M;
vector<int> E[MAXN];
int a[MAXN], b[MAXN];
long long c[MAXN];
int color[MAXN];
vector<int> out;
long long sol[MAXN];
vector<int> ch[MAXN];
void load() {
  scanf("%d%d", &N, &M);
  for (int i = 1; i <= N; i++) scanf("%lld", c + i);
  for (int i = 0; i < M; i++) scanf("%d%d", a + i, b + i);
}
void dfs(int x, int p) {
  color[x] = color[p] ^ 1;
  for (auto it : E[x]) {
    int nxt = a[it] + b[it] - x;
    if (nxt == p) continue;
    if (color[nxt] != -1) {
      out.push_back(it);
      continue;
    }
    ch[x].push_back(it);
    dfs(nxt, x);
  }
}
long long calc(int x) {
  long long res = 0;
  for (auto it : ch[x]) {
    int nxt = a[it] + b[it] - x;
    sol[it] = c[nxt] - calc(nxt);
    res += sol[it];
  }
  return res;
}
void solve() {
  for (int i = 0; i < M; i++) {
    E[a[i]].push_back(i);
    E[b[i]].push_back(i);
  }
  memset(color, -1, sizeof color);
  color[0] = 1;
  dfs(1, 0);
  long long diff = 0;
  for (int i = 1; i <= N; i++) diff += color[i] ? c[i] : -c[i];
  bool ok = false;
  for (auto it : out)
    if (color[a[it]] == color[b[it]]) {
      sol[it] = color[a[it]] ? diff / 2 : -diff / 2;
      c[a[it]] -= sol[it];
      c[b[it]] -= sol[it];
      ok = true;
      break;
    }
  if (!ok && diff) {
    puts("NO");
    return;
  }
  calc(1);
  puts("YES");
  for (int i = 0; i < M; i++) printf("%lld\n", sol[i]);
}
int main() {
  load();
  solve();
  return 0;
}
