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() {
  char c = getchar();
  int x = 0, f = 1;
  while (c < '0' || c > '9') f = (c == '-') ? -1 : f, c = getchar();
  while (c >= '0' && c <= '9') x = x * 10 + c - 48, c = getchar();
  return x * f;
}
const int N = 1e5 + 10;
struct Edge {
  int nxt, point;
} edge[N << 1];
int tot = 1, head[N];
int dep[N];
pair<int, int> e[N];
long long f[N], w[N], c[N], now[N];
int Id[N << 1];
bool used[N];
void add_edge(int u, int v) {
  edge[++tot].nxt = head[u];
  edge[tot].point = v;
  head[u] = tot;
}
void dfs(int u, int fa) {
  dep[u] = dep[fa] + 1;
  used[u] = 1;
  for (int i = head[u]; i; i = edge[i].nxt) {
    int v = edge[i].point;
    if (used[v]) continue;
    dfs(v, u);
    f[Id[i]] = c[v] - now[v];
    now[u] += f[Id[i]];
  }
}
void calc(int u) {
  used[u] = 1;
  for (int i = head[u]; i; i = edge[i].nxt) {
    int v = edge[i].point;
    if (used[v]) continue;
    calc(v);
    f[Id[i]] = c[v] - now[v];
    now[u] += f[Id[i]];
  }
}
int main() {
  int n = read(), m = read();
  long long mx = 2ll * n * n;
  for (int i = 1; i <= n; ++i) c[i] = read();
  for (int i = 1; i <= m; ++i) {
    int u = read(), v = read();
    e[i] = make_pair(u, v);
    add_edge(u, v);
    add_edge(v, u);
    Id[tot] = Id[tot ^ 1] = i;
  }
  dfs(1, 0);
  if (now[1] == c[1]) {
    for (int i = 1; i <= m; ++i) {
      if (-mx <= f[i] && mx >= f[i]) continue;
      puts("NO");
      return 0;
    }
    puts("YES");
    for (int i = 1; i <= m; ++i) printf("%lld\n", f[i]);
  } else {
    if ((c[1] - now[1]) & 1) return puts("NO"), 0;
    for (int i = 1; i <= m; ++i) {
      int u = e[i].first, v = e[i].second;
      if (abs(dep[u] - dep[v]) & 1)
        continue;
      else {
        long long x = ((c[1] - now[1]) / 2);
        if (abs(dep[u] - dep[1]) & 1) x = -x;
        memset(now, 0, sizeof(now));
        memset(f, 0, sizeof(f));
        memset(used, 0, sizeof(used));
        f[i] = x;
        now[u] = x, now[v] = x;
        calc(1);
        assert(c[1] == now[1]);
        for (int i = 1; i <= m; ++i) {
          if (-mx <= f[i] && mx >= f[i]) continue;
          return puts("NO"), 0;
        }
        puts("YES");
        for (int i = 1; i <= m; ++i) printf("%lld\n", f[i]);
        return 0;
      }
    }
    puts("NO");
  }
  return 0;
}
