#include <bits/stdc++.h>
using namespace std;
template <class c>
struct rge {
  c b, e;
};
template <class c>
rge<c> range(c i, c j) {
  return rge<c>{i, j};
}
template <class c>
auto dud(c* x) -> decltype(cerr << *x, 0);
template <class c>
char dud(...);
struct debug {
  template <class c>
  debug& operator<<(const c&) {
    return *this;
  }
};
const int nax = 1e5 + 5;
int h[nax];
long long should[nax], answer[nax];
bool vis[nax];
vector<pair<int, int>> w[nax];
long long EVEN = 0, ODD = 0;
pair<pair<int, int>, int> spec;
vector<pair<int, int>> children[nax];
void dfs_one(int a) {
  if (h[a] % 2)
    ODD += should[a];
  else
    EVEN += should[a];
  assert(!vis[a]);
  vis[a] = true;
  for (pair<int, int> edge : w[a]) {
    int b = edge.first;
    if (!vis[b]) {
      children[a].push_back(edge);
      h[b] = h[a] + 1;
      dfs_one(b);
    } else if ((h[a] - h[b]) % 2 == 0) {
      spec = make_pair(make_pair(a, b), edge.second);
    }
  }
}
void dfs_two(int a) {
  for (pair<int, int> edge : children[a]) {
    int b = edge.first;
    dfs_two(b);
    answer[edge.second] = should[b];
    should[a] -= should[b];
    should[b] = 0;
  }
}
void NO() {
  puts("NO");
  exit(0);
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%lld", &should[i]);
  for (int i = 1; i <= m; ++i) {
    int a, b;
    scanf("%d%d", &a, &b);
    w[a].push_back({b, i});
    w[b].push_back({a, i});
  }
  dfs_one(1);
  long long need = EVEN - ODD;
  if (need) {
    if (need % 2 != 0) NO();
    need /= 2;
    debug() << " ["
            << "need"
               ": "
            << (need)
            << "] "
               " ["
            << "spec"
               ": "
            << (spec) << "] ";
    int id = spec.second;
    if (id == 0) NO();
    if (h[spec.first.first] % 2 == 1) need *= -1;
    answer[id] = need;
    should[spec.first.first] -= need;
    should[spec.first.second] -= need;
  }
  dfs_two(1);
  assert(should[1] == 0);
  puts("YES");
  for (int i = 1; i <= m; ++i) printf("%lld\n", answer[i]);
}
