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 inf = 1e9;
const long long Inf = 1e18;
const int N = 1e5 + 10;
const int mod = 0;
int gi() {
  int x = 0, o = 1;
  char ch = getchar();
  while ((ch < '0' || ch > '9') && ch != '-') ch = getchar();
  if (ch == '-') o = -1, ch = getchar();
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x * o;
}
template <typename T>
bool chkmax(T &a, T b) {
  return a < b ? a = b, 1 : 0;
};
template <typename T>
bool chkmin(T &a, T b) {
  return a > b ? a = b, 1 : 0;
};
int add(int a, int b) { return a + b >= mod ? a + b - mod : a + b; }
int sub(int a, int b) { return a - b < 0 ? a - b + mod : a - b; }
void inc(int &a, int b) { a = (a + b >= mod ? a + b - mod : a + b); }
void dec(int &a, int b) { a = (a - b < 0 ? a - b + mod : a - b); }
int to[N << 1], nxt[N << 1], ans[N], h[N], fa[N], c[N], u[N], v[N], dep[N],
    e[N];
int getf(int x) { return x == fa[x] ? x : fa[x] = getf(fa[x]); }
void adde(int u, int v, int i) {
  to[i << 1] = v, nxt[i << 1] = h[u], h[u] = i << 1;
  to[i << 1 | 1] = u, nxt[i << 1 | 1] = h[v], h[v] = i << 1 | 1;
}
void dfs(int u, int fa) {
  for (int i = h[u]; i; i = nxt[i])
    if (to[i] != fa) dep[to[i]] = dep[u] ^ 1, dfs(to[i], u);
}
void work(int u) {
  for (int i = h[u]; i; i = nxt[i]) {
    int v = to[i];
    if (v != fa[u]) {
      fa[v] = u, work(v);
      ans[i >> 1] = c[v], e[v] = i >> 1, c[u] -= c[v];
    }
  }
}
int main() {
  int n = gi(), m = gi();
  auto out = [&]() {
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%d\n", ans[i]);
    exit(0);
  };
  for (int i = 1; i <= n; i++) c[i] = gi(), fa[i] = i;
  for (int i = 1; i <= m; i++) {
    int x = gi(), y = gi();
    if (getf(x) == getf(y))
      u[i] = x, v[i] = y;
    else
      fa[fa[x]] = fa[y], adde(x, y, i);
  }
  dfs(1, 0);
  for (int i = 1; i <= m; i++)
    if (u[i] && dep[u[i]] == dep[v[i]]) {
      fa[u[i]] = 0, work(u[i]);
      int x = c[u[i]] / 2;
      ans[i] = x;
      for (int t = v[i]; t != u[i]; t = fa[t]) x = -x, ans[e[t]] += x;
      out();
    }
  work(1);
  if (c[1] == 0)
    out();
  else
    puts("NO");
  return 0;
}
