#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
int n, m;
vector<int> g[maxn];
bool marked[maxn];
int h[maxn];
long long int c[maxn];
long long int ans[maxn];
map<pair<int, int>, int> edge;
int part1 = 0, part2 = 0;
int cycleIndex = -1;
int cycleIndex1 = -1;
int par[maxn];
long long int dfs(int v, int p) {
  marked[v] = true;
  if (h[v] % 2 == 0)
    part1 += c[v];
  else
    part2 += c[v];
  par[v] = p;
  long long int temp = 0;
  for (int u : g[v]) {
    if (!marked[u]) {
      h[u] = h[v] + 1;
      temp += dfs(u, v);
    } else if (u != p) {
      if ((h[v] - h[u]) % 2 == 0 && cycleIndex == -1) {
        cycleIndex = v;
        cycleIndex1 = u;
      }
    }
  }
  if (p != -1) ans[edge[make_pair(v, p)]] = c[v] - temp;
  return c[v] - temp;
}
long long int dfs2(int v, int p) {
  marked[v] = true;
  long long int temp = 0;
  for (int u : g[v]) {
    if (!marked[u]) {
      temp += dfs2(u, v);
    }
  }
  if (p != -1) ans[edge[make_pair(v, p)]] = c[v] - temp;
  return c[v] - temp;
}
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> c[i];
  for (int i = 0; i < m; i++) {
    int v, u;
    cin >> v >> u;
    v--;
    u--;
    edge[make_pair(v, u)] = i;
    edge[make_pair(u, v)] = i;
    g[v].push_back(u);
    g[u].push_back(v);
  }
  dfs(0, -1);
  if (cycleIndex == -1) {
    if (part1 == part2) {
      cout << "YES" << endl;
      for (int i = 0; i < m; i++) cout << ans[i] << endl;
    } else {
      cout << "NO" << endl;
    }
  } else {
    memset(ans, 0, sizeof ans);
    memset(marked, false, sizeof marked);
    int x = dfs2(cycleIndex, -1);
    x /= 2;
    ans[edge[make_pair(cycleIndex, cycleIndex1)]] += x;
    while (cycleIndex != cycleIndex1) {
      ans[edge[make_pair(cycleIndex, par[cycleIndex])]] += x;
      cycleIndex = par[cycleIndex];
      x = -x;
    }
    cout << "YES" << endl;
    for (int i = 0; i < m; i++) cout << ans[i] << endl;
  }
  return 0;
}
