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 maxn = 1E5 + 77;
struct REDGE {
  int x, y, v;
} redges[maxn];
struct EDGE {
  int to, next, idx;
} edges[maxn * 2];
int cEdge = 1, head[maxn];
void addEdge(int from, int to, int idx) {
  edges[cEdge] = (EDGE){to, head[from], idx};
  head[from] = cEdge++;
}
int N, M, C[maxn];
int ek;
int sum[2];
int vis[maxn];
bool dfs1(int u, int d, int t) {
  if (vis[u]) {
    if (vis[u] != d) {
      ek = edges[t].idx;
      return false;
    } else {
      return true;
    }
  }
  vis[u] = d;
  sum[d - 1] += C[u];
  for (int k = head[u]; k; k = edges[k].next) {
    int v = edges[k].to;
    if (!dfs1(v, 3 - d, k)) return false;
  }
  return true;
}
bool bipart() { return dfs1(1, 1, 0); }
void dfs2(int u, int t) {
  int suc = 0;
  vis[u] = 1;
  for (int k = head[u]; k; k = edges[k].next) {
    int v = edges[k].to;
    if (vis[v]) continue;
    dfs2(v, k);
    suc += redges[edges[k].idx].v;
  }
  if (t) redges[edges[t].idx].v = C[u] - suc;
}
int pk[maxn];
int vis3[maxn];
void dfs3(int u) {
  vis3[u] = true;
  for (int k = head[u]; k; k = edges[k].next) {
    int v = edges[k].to;
    if (vis3[v]) continue;
    if (!vis[v] || vis[v] == vis[u]) continue;
    pk[v] = edges[k].idx;
    dfs3(v);
  }
}
bool vis4[maxn];
void dfs4(int u) {
  int suc = 0;
  vis4[u] = true;
  for (int k = head[u]; k; k = edges[k].next) {
    int v = edges[k].to;
    if (vis4[v]) continue;
    if (pk[v] && pk[v] != edges[k].idx) continue;
    pk[v] = edges[k].idx;
    dfs4(v);
    suc += redges[pk[v]].v;
  }
  if (pk[u]) redges[pk[u]].v = C[u] - suc;
}
int altro(int k, int v) {
  if (redges[k].x == v)
    return redges[k].y;
  else
    return redges[k].x;
}
void solveNoBipart() {
  int r = redges[ek].x;
  dfs3(r);
  dfs4(r);
  int d = C[r];
  for (int k = head[r]; k; k = edges[k].next) {
    d -= redges[edges[k].idx].v;
  }
  d >>= 1;
  redges[ek].v = d;
  for (int u = redges[ek].y; u != r; u = altro(pk[u], u)) {
    d = -d;
    redges[pk[u]].v += d;
  }
}
int main() {
  scanf("%d%d", &N, &M);
  for (int i = 1; i <= N; ++i) scanf("%d", C + i);
  for (int i = 1; i <= M; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    addEdge(x, y, i);
    addEdge(y, x, i);
    redges[i] = (REDGE){x, y};
  }
  if (bipart()) {
    if (sum[0] == sum[1]) {
      memset(vis, 0, sizeof(vis));
      dfs2(1, 0);
    } else {
      printf("NO\n");
      return 0;
    }
  } else {
    solveNoBipart();
  }
  printf("YES\n");
  for (int i = 1; i <= M; ++i) {
    printf("%d\n", redges[i].v);
  }
}
