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 i64 = long long;
constexpr int maxn(100000);
template <class _Tp>
inline _Tp Abs(const _Tp& v) {
  return v < 0 ? -v : v;
}
template <class _Tp>
inline _Tp Min(const _Tp& x, const _Tp& y) {
  return x < y ? x : y;
}
template <class _Tp>
inline _Tp Max(const _Tp& x, const _Tp& y) {
  return x > y ? x : y;
}
namespace IOManager {
constexpr int FILESZ(131072);
char buf[FILESZ];
const char *ibuf = buf, *tbuf = buf;
struct IOManager {
  inline char gc() {
    return (ibuf == tbuf) &&
                   (tbuf = (ibuf = buf) + fread(buf, 1, FILESZ, stdin),
                    ibuf == tbuf)
               ? EOF
               : *ibuf++;
  }
  template <class _Tp>
  inline operator _Tp() {
    _Tp s = 0u;
    char c = gc(), w = 0;
    for (; c < 48; c = gc()) (c == 45) && (w = 1);
    for (; c > 47; c = gc()) s = (_Tp)(s * 10u + c - 48u);
    return w ? -s : s;
  }
};
}  // namespace IOManager
IOManager::IOManager io;
struct Edge {
  int v, idx;
  Edge* las;
  inline Edge* init(const int to, const int iidx, Edge* const& ls) {
    return v = to, idx = iidx, las = ls, this;
  }
} * las[maxn + 1];
inline void lnk(const int u, const int v, const int idx) {
  static Edge pool[maxn << 1], *alc = pool - 1;
  las[u] = (++alc)->init(v, idx, las[u]);
  las[v] = (++alc)->init(u, idx, las[v]);
}
struct Edge2 {
  int u, v;
} e[maxn + 1];
int ufs[maxn + 1];
inline int Anc(const int _) { return _ == ufs[_] ? _ : ufs[_] = Anc(ufs[_]); }
i64 c[maxn + 1], tc[maxn + 1];
i64 w[maxn + 1];
unsigned char dep[maxn + 1];
void calc(const int now, const int Fa, const int idx) {
  i64& t = c[now];
  for (Edge* o = las[now]; o; o = o->las)
    if (o->v != Fa)
      dep[o->v] = !dep[now], calc(o->v, now, o->idx), t -= w[o->idx];
  w[idx] = t;
  t = 0;
}
int main() {
  const int n = io, m = io;
  for (int i = 1; i <= n; ++i) c[i] = io, ufs[i] = i;
  for (int i = 1; i <= m; ++i)
    if (Anc(e[i].u = io) != Anc(e[i].v = io))
      ufs[ufs[e[i].u]] = ufs[e[i].v], lnk(e[i].u, e[i].v, i);
  memcpy(tc + 1, c + 1, n << 3);
  calc(1, 0, 0);
  memcpy(c + 1, tc + 1, n << 3);
  if (i64 res = *w) {
    if (Abs(res) & 1) return puts("NO"), 0;
    for (int i = 1; i <= m; ++i)
      if (dep[e[i].u] == dep[e[i].v]) {
        if (dep[e[i].u])
          w[i] = -res / 2ll;
        else
          w[i] = res / 2ll;
        c[e[i].u] -= w[i];
        c[e[i].v] -= w[i];
        res = 0;
        break;
      }
    if (res) return puts("NO"), 0;
  }
  calc(1, 0, 0);
  puts("YES");
  for (int i = 1; i <= m; ++i) printf("%lld\n", w[i]);
  return 0;
}
