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 = 100010;
const int inf = 2147483647;
const double pi = acos(-1.0);
int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x * f;
}
int n, m, dep[Maxn], fa[Maxn], from[Maxn];
long long c[Maxn], v[Maxn];
struct Edge {
  int y, next;
} e[Maxn << 1];
int len = 1, last[Maxn];
void ins(int x, int y) {
  int t = ++len;
  e[t].y = y;
  e[t].next = last[x];
  last[x] = t;
}
int p = -1, pp, edge, root;
long long tmp;
bool is[Maxn];
void dfs(int x, int Fa, int From) {
  dep[x] = dep[Fa] + 1;
  fa[x] = Fa;
  from[x] = From;
  long long s = 0;
  for (int i = last[x]; i; i = e[i].next) {
    int y = e[i].y;
    if (From != -1 && From == (i ^ 1)) continue;
    if (dep[y] == -1)
      dfs(y, x, i), s += v[i >> 1];
    else if (dep[x] > dep[y]) {
      if ((dep[x] - dep[y]) % 2 == 0) {
        if (root == 1) p = x, pp = y, edge = i;
        if (y == root) {
          pp = x;
          edge = i;
        }
      }
    }
  }
  if (From != -1) v[From >> 1] = c[x] - s;
  if (x == root) tmp = c[x] - s;
}
void work(int p) {
  memset(v, 0, sizeof(v));
  memset(dep, -1, sizeof(dep));
  dep[0] = 0;
  root = p;
  dfs(p, 0, -1);
  if (abs(tmp) & 1)
    puts("NO");
  else {
    v[edge >> 1] = tmp / 2ll;
    int u = 0, x = pp;
    while (x != p) {
      if (!u)
        v[from[x] >> 1] -= tmp / 2ll;
      else
        v[from[x] >> 1] += tmp / 2ll;
      u ^= 1;
      x = fa[x];
    }
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%lld\n", v[i]);
  }
}
int main() {
  memset(v, 0, sizeof(v));
  memset(dep, -1, sizeof(dep));
  n = read(), m = read();
  for (int i = 1; i <= n; i++) c[i] = read();
  for (int i = 1; i <= m; i++) {
    int x = read(), y = read();
    ins(x, y), ins(y, x);
  }
  dep[0] = 0;
  root = 1;
  dfs(1, 0, -1);
  if (tmp != 0 && p == -1) return puts("NO"), 0;
  if (tmp == 0) {
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%lld\n", v[i]);
    return 0;
  }
  work(p);
}
