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>
int CH, NEG;
template <typename TP>
inline void read(TP& ret) {
  ret = NEG = 0;
  while (CH = getchar(), CH < '!')
    ;
  if (CH == '-') NEG = true, CH = getchar();
  while (ret = ret * 10 + CH - '0', CH = getchar(), CH > '!')
    ;
  if (NEG) ret = -ret;
}
int star[100010LL], e[3][100010LL << 1], te = 1;
inline void AddEdge(int u, int v, int w) {
  te++;
  e[0][te] = v;
  e[1][te] = star[u];
  star[u] = te;
  e[2][te] = w;
  te++;
  e[0][te] = u;
  e[1][te] = star[v];
  star[v] = te;
  e[2][te] = w;
}
int n, m;
long long c[100010LL], cc[100010LL], ans[100010LL];
int pre[100010LL];
bool col[100010LL], vis[100010LL];
bool odd = false;
int eu, ev, ei;
void dfs(int u = 1) {
  vis[u] = true;
  for (int p = star[u], v; p; p = e[1][p])
    if (v = e[0][p], !vis[v]) {
      pre[v] = p;
      col[v] = col[u] ^ 1;
      dfs(v);
      cc[u] -= (ans[e[2][p]] = cc[v]);
    } else if (col[u] == col[v])
      odd = true, eu = u, ev = v, ei = e[2][p];
}
void dfs2(int u) {
  vis[u] = false;
  for (int p = star[u], v; p; p = e[1][p])
    if (v = e[0][p], vis[v] && (col[v] ^ col[u]) && e[2][p] != ei) {
      pre[v] = p;
      dfs2(v);
      c[u] -= (ans[e[2][p]] = c[v]);
    }
}
int main() {
  int i, a, b;
  long long delta, sig;
  read(n), read(m);
  for (i = (1); i <= (n); i++) read(c[i]), cc[i] = c[i];
  for (i = (1); i <= (m); i++) read(a), read(b), AddEdge(a, b, i);
  dfs();
  if (cc[1] == 0) {
    puts("YES");
    for (i = (1); i <= (m); i++) printf("%lld\n", ans[i]);
    goto END;
  }
  if (!odd) {
    puts("NO");
    goto END;
  }
  memset(ans, 0, sizeof ans);
  dfs2(eu);
  delta = c[eu] / 2LL;
  sig = -1LL;
  while (ev != eu) {
    ans[e[2][pre[ev]]] += sig * delta;
    ev = e[0][pre[ev] ^ 1];
    sig *= -1LL;
  }
  ans[ei] += delta;
  puts("YES");
  for (i = (1); i <= (m); i++) printf("%lld\n", ans[i]);
END:
  getchar(), getchar();
  return 0;
}
