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 MAXN = 150000 + 10;
struct Edge {
  int from, to, id, nx;
} edg[MAXN << 1];
int G[MAXN], p[MAXN], dep[MAXN], n, m, edgn = 0, ord[MAXN];
long long c[MAXN], ans[MAXN];
bool cmpdep(int u, int v) { return dep[u] > dep[v]; }
bool dfs(int u);
void greedy();
inline void AddEdg(int u, int v, int id) {
  edg[edgn++] = (Edge){u, v, id, G[u]};
  G[u] = edgn - 1;
  edg[edgn++] = (Edge){v, u, id, G[v]};
  G[v] = edgn - 1;
}
inline bool ddfs(int rt) {
  for (int i = 0; i <= n; i++) p[i] = -1, dep[i] = 0;
  dep[rt] = 1;
  return dfs(rt);
}
inline int odde(int u) {
  for (int i = G[u]; i != -1; i = edg[i].nx)
    if (((dep[u] ^ dep[edg[i].to]) & 1) == 0) return i;
  return -1;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i <= n; i++) G[i] = -1;
  long long sgmc = 0;
  for (int i = 1; i <= n; i++) {
    scanf("%I64d", &c[i]);
    sgmc += c[i];
  }
  if (sgmc % 2 != 0) puts("NO"), exit(0);
  for (int i = 0, u, v; i < m; i++) {
    scanf("%d%d", &u, &v);
    AddEdg(u, v, i + 1);
  }
  bool fflag = c[1] == -37690 && c[2] == 30252 && c[3] == 3744;
  if (ddfs(1)) {
    int rt;
    for (rt = n; rt >= 1; rt--)
      if (odde(rt) != -1) break;
    ddfs(rt);
    if (fflag) printf("rt=%d\n");
    greedy();
    long long delta = c[rt] / 2;
    if (fflag) printf("delta= %d\n", delta);
    for (int i = odde(rt); i != -1; i = p[edg[i].to], delta = -delta) {
      ans[edg[i].id] += delta;
    }
  } else {
    long long lf = 0, ri = 0;
    for (int u = 1; u <= n; u++)
      if (dep[u] & 1)
        lf += c[u];
      else
        ri += c[u];
    if (lf != ri)
      puts("NO"), exit(0);
    else
      greedy();
  }
  puts("YES");
  for (int i = 1; i <= m; i++) printf("%I64d\n", ans[i]);
  return 0;
}
bool dfs(int u) {
  bool res = false;
  for (int i = G[u]; i != -1; i = edg[i].nx) {
    int v = edg[i].to;
    if (!dep[v]) {
      dep[v] = dep[u] + 1;
      p[v] = i ^ 1;
      res |= dfs(v);
    } else if (((dep[v] ^ dep[u]) & 1) == 0)
      res = true;
  }
  return res;
}
void greedy() {
  for (int i = 1; i <= n; i++) ord[i] = i;
  sort(ord + 1, ord + n + 1, cmpdep);
  for (int i = 1; i < n; i++) {
    int u = ord[i];
    Edge e = edg[p[u]];
    ans[e.id] = c[u];
    c[e.to] -= c[u];
  }
}
