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 IINF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fll;
const double DINF = numeric_limits<double>::infinity();
const int MOD = 1000000007;
const double EPS = 1e-9;
const int DX[] = {1, 0, -1, 0, 1, -1, 1, -1};
const int DY[] = {0, 1, 0, -1, 1, -1, -1, 1};
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long sqr(long long x) { return x * x; }
long long sqr(int x) { return (long long)x * x; }
double sqr(double x) { return x * x; }
long double sqr(long double x) { return x * x; }
mt19937 mmtw(960172);
long long rnd(long long x, long long y) {
  static uniform_int_distribution<long long> d;
  return d(mmtw) % (y - x + 1) + x;
}
const int N = 100179;
int n, m;
vector<pair<int, int> > e[N];
vector<int> e1[N];
int col[N];
int pred[N];
int predI[N];
long long c[N];
vector<pair<int, int> > edges;
long long ans[N];
void dfs(int v, int cc, int p = -1, int pi = -1) {
  if (col[v] != -1) return;
  col[v] = cc;
  pred[v] = p;
  predI[v] = pi;
  if (p != -1) e1[p].push_back(v);
  for (pair<int, int> nv : e[v]) dfs(nv.first, cc ^ 1, v, nv.second);
}
void dfs2(int v) {
  for (int nv : e1[v]) {
    dfs2(nv);
    long long x = c[nv];
    ans[predI[nv]] += x;
    c[nv] -= x;
    c[v] -= x;
  }
}
int main() {
  ios::sync_with_stdio(false);
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; ++i) scanf("%lld", &c[i]);
  for (int i = 0; i < m; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    --x;
    --y;
    e[x].push_back({y, i});
    e[y].push_back({x, i});
    edges.push_back({x, y});
  }
  memset(col, -1, sizeof(col));
  dfs(0, 0, -1);
  long long sum[2] = {0, 0};
  for (int i = 0; i < n; ++i) sum[col[i]] += c[i];
  if ((sum[0] - sum[1]) % 2 != 0) {
    cout << "NO\n";
    return 0;
  }
  if (sum[0] != sum[1]) {
    bool ok = false;
    for (int i = 0; i < m; ++i) {
      int x = edges[i].first;
      int y = edges[i].second;
      if (col[x] == col[y]) {
        ok = true;
        ans[i] = (sum[col[x]] - sum[col[x] ^ 1]) / 2;
        c[x] -= ans[i];
        c[y] -= ans[i];
        break;
      }
    }
    if (!ok) {
      cout << "NO\n";
      return 0;
    }
  }
  dfs2(0);
  cout << "YES\n";
  for (int i = 0; i < m; ++i) cout << ans[i] << "\n";
  return 0;
}
