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;
template <typename T>
void dbg(T a) {}
template <typename T, typename... Arg>
void dbg(T a, Arg... arg) {}
const int maxn = (1e6) + 7;
const int inf = (1e9) + 7;
const long long LLinf = (1e18) + 7;
const long double eps = 1e-9;
const long long mod = 1e9 + 7;
set<pair<int, int> > wek[maxn];
vector<int> cykl;
int val[maxn];
int wyjeb[maxn];
stack<int> stos;
vector<pair<int, int> > kraw;
int stan[maxn];
long long wart[maxn];
bool vis[maxn];
void rob(int x, int f) {
  vis[x] = 1;
  int numer = -1;
  for (auto s : wek[x]) {
    if (s.first == f)
      numer = s.second;
    else if (vis[s.first] == 0)
      rob(s.first, x);
  }
  if (numer != -1) {
    wart[numer] += val[x];
    val[f] -= val[x];
    val[x] = 0;
  }
}
inline void usu(int x) {
  if (stos.size() && stos.top() == x) stos.pop();
}
inline void sciagaj(int x) {
  if (cykl.size() > 1) {
    cykl.pop_back();
    return;
  }
  while (kraw[stos.top()].first != x && kraw[stos.top()].second != x) {
    cykl.push_back(stos.top());
    stos.pop();
  }
  cykl.push_back(stos.top());
  stos.pop();
}
void dfs(int x, int f) {
  for (auto s : wek[x]) {
    if (s.first == f) continue;
    if (stan[s.first] == 0) {
      stan[s.first] = stan[x] ^ 1;
      stos.push(s.second);
      dfs(s.first, x);
      usu(s.second);
    } else if (stan[s.first] == stan[x]) {
      cykl.push_back(s.second);
      sciagaj(s.first);
    } else {
      wyjeb[s.second] = 1;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> val[i];
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    wek[a].insert({b, i});
    wek[b].insert({a, i});
    kraw.push_back({a, b});
  }
  for (int i = 1; i <= n; i++) {
    val[i] -= wek[i].size();
    assert((val[i] & 1) == 0);
  }
  stan[1] = 2;
  dfs(1, 0);
  for (auto s : cykl) dbg(kraw[s].first, kraw[s].second);
  for (int i = 0; i < m; i++)
    if (wyjeb[i] == 1) {
      dbg(i);
      wek[kraw[i].first].erase({kraw[i].second, i});
      wek[kraw[i].second].erase({kraw[i].first, i});
    }
  if (cykl.size()) {
    int a = kraw[cykl[0]].first;
    if (a != kraw[cykl.back()].first && a != kraw[cykl.back()].second)
      a = kraw[cykl[0]].second;
    rob(a, 0);
    assert((val[a] & 1) == 0);
    long long ile = val[a] / 2LL;
    long long f = 1;
    for (auto s : cykl) {
      wart[s] += f * ile;
      f *= -1;
    }
  } else {
    rob(1, 0);
    if (val[1] != 0) {
      cout << "NO\n";
      return 0;
    }
  }
  cout << "YES\n";
  for (int i = 0; i < m; i++) cout << wart[i] + 1 << "\n";
  return 0;
}
