#include <bits/stdc++.h>
using namespace std;
int ex[100005], ey[100005];
vector<int> g[100005];
int n, m, c[100005];
long long a[100005], r[100005], s[2];
vector<int> g2[100005];
void dfs0(int x) {
  s[c[x]] += a[x];
  for (int i : g[x]) {
    int y = ex[i] ^ ey[i] ^ x;
    if (c[y] < 0) {
      c[y] = 1 - c[x];
      g2[x].push_back(i);
      g2[y].push_back(i);
      dfs0(y);
    }
  }
}
void dfs1(int x, int f) {
  for (int i : g2[x]) {
    int y = ex[i] ^ ey[i] ^ x;
    if (y == f) continue;
    dfs1(y, x);
    r[i] = a[y];
    a[x] -= r[i];
  }
}
int main() {
  scanf("%d%d", &n, &m);
  long long ss = 0;
  for (int i = 0, ThxDem = n; i < ThxDem; ++i) scanf("%lld", a + i), ss += a[i];
  for (int i = 0, ThxDem = m; i < ThxDem; ++i) {
    scanf("%d%d", ex + i, ey + i);
    ex[i]--;
    ey[i]--;
    g[ex[i]].push_back(i);
    g[ey[i]].push_back(i);
  }
  memset(c, -1, sizeof(c));
  c[0] = 0;
  dfs0(0);
  for (int i = 0, ThxDem = m; i < ThxDem; ++i)
    if (c[ex[i]] == c[ey[i]]) {
      r[i] = (s[c[ex[i]]] - s[c[ex[i]] ^ 1]) / 2;
      a[ex[i]] -= r[i];
      a[ey[i]] -= r[i];
      s[c[ex[i]]] -= 2 * r[i];
      break;
    }
  if (s[0] != s[1]) {
    puts("NO");
    return 0;
  }
  dfs1(0, -1);
  puts("YES");
  for (int i = 0, ThxDem = m; i < ThxDem; ++i) printf("%lld\n", r[i]);
  return 0;
}
