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 MAX = 1 << 19;
vector<pair<int, int> > V[MAX];
long long rje[MAX];
long long val[MAX];
int bio[MAX], disc[MAX], par[MAX], vr;
int col[MAX];
int ea[MAX], eb[MAX];
int done[MAX];
int dfs_bip(int node, int cl) {
  if (col[node] != -1) return col[node] == cl;
  col[node] = cl;
  for (auto it : V[node])
    if (!dfs_bip(it.first, 1 ^ cl)) return 0;
  return 1;
}
int bip() {
  memset(col, -1, sizeof col);
  return dfs_bip(0, 0);
}
int dub[MAX];
int jelbip;
vector<int> Ciklus;
vector<int> CikEdge;
int incik[MAX];
void uzmi_cik(int node, int gor) {
  Ciklus.push_back(node);
  for (;;) {
    assert(par[node] != -1);
    node = par[node];
    Ciklus.push_back(node);
    if (node == gor) break;
  }
}
void nadi_cik(int node, int pr) {
  dub[node] = (pr == -1) ? 0 : (dub[pr] + 1);
  bio[node] = 1;
  disc[node] = vr++;
  par[node] = pr;
  for (auto it : V[node]) {
    if (it.first == pr) continue;
    if (bio[it.first] && disc[it.first] < disc[node]) {
      if (jelbip || ((dub[node] - dub[it.first]) % 2 == 0)) {
        uzmi_cik(node, it.first);
        return;
      }
    }
    if (!bio[it.first]) {
      nadi_cik(it.first, node);
      if (Ciklus.size()) return;
    }
  }
}
int deg[MAX];
void set_edge(int id, long long vl) {
  done[id] = 1;
  int a = ea[id], b = eb[id];
  rje[id] = vl;
  deg[a]--;
  deg[b]--;
  val[a] -= vl;
  val[b] -= vl;
}
void dfs_sol(int node) {
  bio[node] = 1;
  for (auto it : V[node]) {
    if (!bio[it.first]) dfs_sol(it.first);
    if (!done[it.second] && !incik[it.second]) {
      if (deg[node] == 1)
        set_edge(it.second, val[node]);
      else if (deg[it.first] == 1)
        set_edge(it.second, val[it.first]);
      else
        set_edge(it.second, rand() & 1 ? 1 : -1);
    }
  }
}
int n, m;
int check() {
  int nope = 0;
  for (int i = 0; i < m; i++)
    if (!done[i]) nope++;
  for (int i = 0; i < n; i++)
    if (val[i]) return 0;
  return 1;
}
void sol_cik() {
  if (Ciklus.empty()) return;
  long long sum = 0;
  int csz = (int)Ciklus.size();
  assert(CikEdge.size() == Ciklus.size());
  for (int i = 0; i < csz; i++) {
    if (!(i % 2))
      sum += val[Ciklus[i]];
    else
      sum -= val[Ciklus[i]];
  }
  assert(sum % 2 == 0);
  set_edge(CikEdge.back(), sum / 2);
  for (int i = 0; i < csz - 1; i++) set_edge(CikEdge[i], val[Ciklus[i]]);
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%lld", &val[i]);
  for (int i = 0; i < m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    a--;
    b--;
    ea[i] = a;
    eb[i] = b;
    V[a].push_back(pair<int, int>(b, i));
    V[b].push_back(pair<int, int>(a, i));
  }
  jelbip = bip();
  nadi_cik(0, -1);
  int csz = (int)Ciklus.size();
  for (int i = 0; i < csz; i++) {
    int a = Ciklus[i], b = Ciklus[(i + 1) % csz];
    for (auto it : V[a])
      if (it.first == b) {
        incik[it.second] = 1;
        CikEdge.push_back(it.second);
      }
  }
  memset(bio, 0, sizeof bio);
  for (int i = 0; i < n; i++) deg[i] = (int)V[i].size();
  if (!Ciklus.empty()) {
    dfs_sol(Ciklus[0]);
    sol_cik();
  } else
    dfs_sol(0);
  if (check()) {
    printf("YES\n");
    for (int i = 0; i < m; i++) printf("%lld\n", rje[i]);
  } else
    printf("NO\n");
  return 0;
}
