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>
const int N = +51;
struct edge {
  int to, next;
} e[N << 1];
int head[N], cnt = 1;
void addedge(int x, int y) {
  e[++cnt] = (edge){y, head[x]}, head[x] = cnt;
  e[++cnt] = (edge){x, head[y]}, head[y] = cnt;
}
struct dsu {
  int p[N];
  int f(int x) { return p[x] ? p[x] = f(p[x]) : x; }
  void m(int x, int y) {
    if ((x = f(x)) != (y = f(y))) p[x] = y;
  }
} _;
int a[N], v[N], c[N], d[N], P[N], mk[N];
void dfs(int x, int p) {
  for (int i = head[x], nx; i; i = e[i].next)
    if ((nx = e[i].to) != p)
      c[nx] = !c[x], d[nx] = d[x] + 1, P[nx] = x, dfs(nx, x), v[x] -= v[nx],
      a[i / 2] += v[nx], v[nx] = 0;
}
int n, m, x[N], y[N];
bool f[N];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%d", v + i);
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", x + i, y + i);
    if (_.f(x[i]) != _.f(y[i]))
      f[i] = true, addedge(x[i], y[i]), _.m(x[i], y[i]);
    else
      cnt += 2;
  }
  c[1] = 1, dfs(1, 0);
  if (v[1] % 2) return puts("NO"), 0;
  if (!v[1]) {
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%d\n", a[i]);
    return 0;
  }
  for (int i = 1, s, t; i <= m; i++) {
    if (f[i] || c[s = x[i]] != c[t = y[i]]) continue;
    int ss = s, tt = t, val;
    if (d[s] < d[t]) std::swap(s, t);
    for (; s; s = P[s]) mk[s] = 1;
    if (mk[t])
      val = d[t] % 2 ? -2 : 2;
    else {
      for (; t && !mk[t];) t = P[t];
      val = d[t] % 2 ? 2 : -2;
    }
    val = v[1] / val, v[ss] -= val, v[tt] -= val, a[i] += val;
    dfs(1, 0);
    puts("YES");
    for (int j = 1; j <= m; j++) printf("%d\n", a[j]);
    return 0;
  }
  puts("NO");
}
