#include <bits/stdc++.h>
using namespace std;
int N, M;
signed long long C[101010];
int U[101010], V[101010];
vector<pair<int, int>> E[101010];
signed long long R[101010];
int col[101010];
signed long long P[2];
int tree[101010];
int in[101010];
void dfs(int cur, int c) {
  col[cur] = c;
  P[c] += C[cur];
  for (auto& e : E[cur]) {
    if (col[e.first] == -1) {
      tree[e.second] = 1;
      dfs(e.first, c ^ 1);
    }
  }
}
void solve() {
  int i, j, k, l, r, x, y;
  string s;
  cin >> N >> M;
  for (i = 0; i < (N); i++) cin >> C[i];
  for (i = 0; i < (M); i++) {
    cin >> U[i] >> V[i];
    U[i]--, V[i]--;
    E[U[i]].push_back({V[i], i});
    E[V[i]].push_back({U[i], i});
  }
  memset(col, 0xff, sizeof(col));
  dfs(0, 0);
  if (P[0] != P[1]) {
    for (i = 0; i < (M); i++)
      if (col[U[i]] == col[V[i]]) break;
    if (i == M) return (void)printf("NO\n");
    R[i] = (P[col[U[i]]] - P[col[U[i]] ^ 1]) / 2;
    C[U[i]] -= R[i];
    C[V[i]] -= R[i];
  }
  queue<int> Q;
  for (i = 0; i < (N); i++) {
    for (auto& e : E[i])
      if (tree[e.second]) in[i]++;
    if (in[i] == 1) Q.push(i);
  }
  while (Q.size()) {
    int cur = Q.front();
    Q.pop();
    int id = -1;
    for (auto& e : E[cur])
      if (tree[e.second]) id = e.second;
    if (id >= 0) {
      int op = U[id] + V[id] - cur;
      R[id] = C[cur];
      tree[id] = 0;
      C[cur] = 0;
      C[op] -= R[id];
      in[op]--;
      if (in[op] == 1) Q.push(op);
    }
  }
  cout << "YES" << endl;
  for (i = 0; i < (M); i++) cout << R[i] << endl;
}
int main(int argc, char** argv) {
  string s;
  int i;
  if (argc == 1) ios::sync_with_stdio(false), cin.tie(0);
  for (i = 0; i < (argc - 1); i++) s += argv[i + 1], s += '\n';
  for (i = 0; i < (s.size()); i++) ungetc(s[s.size() - 1 - i], stdin);
  cout.tie(0);
  solve();
  return 0;
}
