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 Imx = 2147483647;
const long long Lbig = 2e18;
const int mod = 1e9 + 7;
struct fastio {
  char s[100000];
  int it, len;
  fastio() { it = len = 0; }
  inline char get() {
    if (it < len) return s[it++];
    it = 0;
    len = fread(s, 1, 100000, stdin);
    if (len == 0)
      return EOF;
    else
      return s[it++];
  }
  bool notend() {
    char c = get();
    while (c == ' ' || c == '\n') c = get();
    if (it > 0) it--;
    return c != EOF;
  }
} _buff;
inline long long getnum() {
  long long r = 0;
  bool ng = 0;
  char c;
  c = _buff.get();
  while (c != '-' && (c < '0' || c > '9')) c = _buff.get();
  if (c == '-') ng = 1, c = _buff.get();
  while (c >= '0' && c <= '9') r = r * 10 + c - '0', c = _buff.get();
  return ng ? -r : r;
}
template <class T>
inline void putnum(T x) {
  if (x < 0) putchar('-'), x = -x;
  register short a[20] = {}, sz = 0;
  while (x) a[sz++] = x % 10, x /= 10;
  if (sz == 0) putchar('0');
  for (int i = sz - 1; i >= 0; i--) putchar('0' + a[i]);
}
inline char getreal() {
  char c = _buff.get();
  while (c <= 32) c = _buff.get();
  return c;
}
int n, m, fa[100111], fe[100111];
int head[100111], nxt[200111], to[200111], tot = 1;
long long ia[200111], a[200111], ans[200111];
int eid = -1;
int dis[100111];
bool vis[100111], inst[100111];
void dfs(int x, int pre = -1) {
  vis[x] = 1;
  inst[x] = 1;
  for (int i = head[x]; i; i = nxt[i]) {
    if ((i >> 1) == pre) continue;
    int u = to[i];
    if (!vis[u]) {
      fa[u] = x;
      fe[u] = i >> 1;
      a[x]--;
      a[u]--;
      ans[i >> 1]++;
      dis[u] = dis[x] + 1;
      dfs(u, i >> 1);
      if (a[u] != 0) {
        assert(x != u);
        ans[i >> 1] += a[u];
        a[x] -= a[u];
        a[u] -= a[u];
      }
    } else if (inst[u]) {
      a[x]--;
      a[u]--;
      ans[i >> 1]++;
      if (dis[u] % 2 == dis[x] % 2) {
        eid = i >> 1;
      }
    }
  }
  inst[x] = 0;
}
void out() {
  puts("YES");
  for (int i = 1; i <= m; i++) putnum(ans[i]), putchar('\n');
  for (int i = 1; i <= n; i++) {
    long long sum = 0;
    for (int j = head[i]; j; j = nxt[j]) {
      sum += ans[j >> 1];
    }
    assert(sum == ia[i]);
  }
  exit(0);
}
void update(int x, long long v) {
  bool f = 1;
  while (x != 1) {
    if (f)
      ans[fe[x]] -= v;
    else
      ans[fe[x]] += v;
    x = fa[x];
    f ^= 1;
  }
}
int main() {
  n = getnum(), m = getnum();
  for (int i = 1; i <= n; i++) a[i] = getnum(), ia[i] = a[i];
  for (int i = 1; i <= m; i++) {
    int x, y;
    x = getnum(), y = getnum();
    nxt[++tot] = head[x];
    head[x] = tot;
    to[tot] = y;
    nxt[++tot] = head[y];
    head[y] = tot;
    to[tot] = x;
  }
  dis[1] = 1;
  dfs(1);
  if (a[1] == 0) {
    out();
  }
  if (eid != -1) {
    int u = to[eid << 1], v = to[eid << 1 | 1];
    int t = dis[u];
    long long coef;
    if (t % 2 == 1)
      coef = +a[1] / 2;
    else
      coef = -a[1] / 2;
    ans[eid] += coef;
    update(u, coef);
    update(v, coef);
    out();
  }
  puts("NO");
  return 0;
}
