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 INF = 0x3fffffff;
const int SINF = 0x7fffffff;
const long long LINF = 0x3fffffffffffffff;
const long long SLINF = 0x7fffffffffffffff;
const int MAXN = 100007;
struct eT {
  void setd(int _u, int _v, int _l) { u = _u, v = _v, last = _l; }
  int u, v, last;
} edge[MAXN * 2];
int n, m;
int ke, la[MAXN];
int c[MAXN];
bool vis[MAXN];
long long ans[MAXN];
int si[MAXN];
bool ins[MAXN];
int stk[MAXN], top;
int kc, cyc[MAXN], ce[MAXN];
void init();
void input();
void work();
bool findcyc(int now, int fa);
long long dfs(int now, int fe);
int main() {
  init();
  input();
  work();
}
void init() { ios::sync_with_stdio(false); }
void input() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%d", &c[i]);
  ke = 0;
  memset(la, -1, sizeof(la));
  int u, v;
  for (int i = 0; i < m; ++i) {
    scanf("%d%d", &u, &v);
    edge[ke].setd(u, v, la[u]);
    la[u] = ke++;
    edge[ke].setd(v, u, la[v]);
    la[v] = ke++;
  }
}
void work() {
  if (findcyc(1, -1)) {
    memset(vis, false, sizeof(vis));
    dfs(cyc[1], -1);
    long long del = c[cyc[1]] / 2;
    cyc[kc + 1] = cyc[1];
    for (int i = 1; i <= kc; ++i) {
      int now = cyc[i];
      for (int j = la[now]; ~j; j = edge[j].last) {
        if (edge[j].v == cyc[i + 1]) {
          if (i & 1)
            ans[j >> 1] += del;
          else
            ans[j >> 1] -= del;
        }
      }
    }
  } else {
    memset(vis, false, sizeof(vis));
    dfs(1, -1);
    if (c[1]) {
      printf("NO\n");
      return;
    }
  }
  printf("YES\n");
  for (int i = 0; i < m; ++i) printf("%I64d\n", ans[i]);
}
bool findcyc(int now, int fa) {
  if (vis[now]) {
    if (ins[now] && ((top - si[now]) & 1)) {
      kc = top - si[now];
      for (int i = 1; i <= kc; ++i) cyc[i] = stk[si[now] + i - 1];
      return true;
    } else
      return false;
  }
  vis[now] = true;
  ins[now] = true;
  si[now] = top;
  stk[top++] = now;
  for (int i = la[now]; ~i; i = edge[i].last) {
    if (edge[i].v ^ fa) {
      if (findcyc(edge[i].v, now)) return true;
    }
  }
  ins[now] = false;
  --top;
  return false;
}
long long dfs(int now, int fe) {
  if (vis[now]) return 0;
  vis[now] = true;
  for (int i = la[now]; ~i; i = edge[i].last) {
    c[now] -= dfs(edge[i].v, i >> 1);
  }
  if (~fe) {
    long long ret = c[now];
    ans[fe] += c[now];
    c[now] = 0;
    return ret;
  } else
    return 0;
}
