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;
int read() {
  int x = 0, f = 1;
  char c = getchar();
  while (!isdigit(c)) {
    if (c == '-') f = 0;
    c = getchar();
  }
  while (isdigit(c)) {
    x = (x << 3) + (x << 1) + (c ^ 48);
    c = getchar();
  }
  return f ? x : -x;
}
const int maxn = 1e5 + 10, maxm = maxn << 1;
int e, to[maxm], nxt[maxm], head[maxn], bel[maxm];
int vis[maxn], dep[maxn], g[maxm], val[maxn], from[maxn], fa[maxn];
vector<pair<int, int> > vec;
void add(int x, int y, int i) {
  to[++e] = y;
  nxt[e] = head[x];
  head[x] = e;
  bel[e] = i;
  to[++e] = x;
  nxt[e] = head[y];
  head[y] = e;
  bel[e] = i;
}
int dfs(int u) {
  vis[u] = 1;
  for (int i = head[u]; i; i = nxt[i]) {
    int v = to[i];
    if (vis[v] && dep[u] < dep[v] && !((dep[v] - dep[u]) & 1))
      vec.push_back(make_pair(u, i));
    if (vis[v]) continue;
    dep[v] = dep[u] + 1;
    from[v] = i;
    fa[v] = u;
    g[bel[i]] = dfs(v);
    val[u] -= g[bel[i]];
  }
  return val[u];
}
int main() {
  int n = read(), m = read();
  for (int i = 1; i <= n; ++i) val[i] = read();
  for (int i = 1; i <= m; ++i) add(read(), read(), i);
  int tmp = dfs(1);
  if (tmp != 0 && (!vec.size() || (tmp & 1))) {
    puts("NO");
    return 0;
  }
  if (tmp != 0) {
    tmp /= 2;
    int x = vec[0].first, y = vec[0].second;
    if (dep[x] & 1) tmp = -tmp;
    g[bel[y]] += tmp;
    tmp = -tmp;
    int u = to[y];
    while (u != x) g[bel[from[u]]] += tmp, tmp = -tmp, u = fa[u];
    tmp <<= 1;
    while (u != 1) g[bel[from[u]]] += tmp, tmp = -tmp, u = fa[u];
  }
  puts("YES");
  for (int i = 1; i <= m; ++i) cout << g[i] << endl;
  return 0;
}
