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 N = 1e5 + 10;
struct edge {
  int to, nxt;
  long long w;
} e[N << 1];
int head[N], tot = 1;
int n, m, vis[N];
long long s[3], a[N], d[N];
void adde(int u, int v) {
  e[++tot] = edge{v, head[u]};
  head[u] = tot;
  return;
}
void Dfs(int u, int fa) {
  vis[u] = 3 - vis[fa];
  s[vis[u]] += a[u];
  for (int i = head[u]; i; i = e[i].nxt) {
    int v = e[i].to;
    if (v == fa || vis[v]) continue;
    Dfs(v, u);
  }
  return;
}
void dfs(int u, int fa) {
  vis[u] = 1;
  for (int i = head[u]; i; i = e[i].nxt) {
    int v = e[i].to;
    if (v == fa || vis[v]) continue;
    dfs(v, u);
    e[i].w = a[v], e[i ^ 1].w = a[v];
    a[u] -= a[v], a[v] = 0;
  }
  return;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%lld", &a[i]);
  int u, v;
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &u, &v);
    adde(u, v), adde(v, u);
  }
  vis[0] = 1;
  Dfs(1, 0);
  int id = -1;
  for (int u = 1; u <= n; u++) {
    for (int i = head[u]; i; i = e[i].nxt) {
      int v = e[i].to;
      if (vis[u] == vis[v]) {
        id = i;
        break;
      }
    }
    if (id != -1) break;
  }
  if (s[1] != s[2]) {
    if (id == -1) return printf("NO\n"), 0;
    u = e[id].to, v = e[id ^ 1].to;
    long long d = s[3 - vis[u]] - s[vis[u]];
    if (d % 2 != 0) return printf("NO\n"), 0;
    a[u] += d / 2, a[v] += d / 2;
    e[id].w = -d / 2, e[id ^ 1].w = -d / 2;
  }
  printf("YES\n");
  memset(vis, 0, sizeof(vis));
  dfs(1, 0);
  for (int i = 2; i <= tot; i += 2) printf("%lld\n", e[i].w);
  return 0;
}
