#include 
using namespace std;
typedef long long ll;
const int maxn = 5e5 + 10;
const ll INF = 1e9;
int a[maxn];
int n;
struct node {
  ll sum, pref_sum, suff_sum, max_sum;
  node () {}
  node(ll x) {
    sum = x;
    pref_sum = x;
    suff_sum = x;
    max_sum = x;
  }
};
node segment_tree[3 * maxn];
node merge_two_nodes(node A, node B) {
  node C;
  C.sum = A.sum + B.sum;
  C.pref_sum = max(A.pref_sum, A.sum + B.pref_sum);
  C.suff_sum = max(B.suff_sum, B.sum + A.suff_sum);
  C.max_sum = max(A.max_sum, max(B.max_sum, A.suff_sum + B.pref_sum));
  return C;
}
void build(int L, int R, int pos) {
  if(L == R) {
    segment_tree[pos] = node(a[L]);
  }
  else {
    int middle = (L + R) / 2;
    build(L, middle, 2 * pos);
    build(middle + 1, R, 2 * pos + 1);
    segment_tree[pos] = merge_two_nodes(segment_tree[2 * pos], segment_tree[2 * pos + 1]);
  }
}
node query(int L, int R, int pos, int i, int j) {
  // L R  i L R j L R
  if(i <= L and R <= j) {
    return segment_tree[pos];
  }
  if(R < i or j < L) {
    return node(-INF);
  }
  int middle = (L + R) / 2;
  return merge_two_nodes(query(L, middle, 2 * pos, i, j), query(middle + 1, R, 2 * pos + 1, i, j));
}
void update(int L, int R, int pos, int idx, int value) {
  if(L == R) {
    segment_tree[pos] = node(value);
    return;
  }
  int middle = (L + R) / 2;
  if(idx <= middle) {
    update(L, middle, 2 * pos, idx, value);
  }
  else {
    update(middle + 1, R, 2 * pos + 1, idx, value);
  }
  segment_tree[pos] = merge_two_nodes(segment_tree[2 * pos], segment_tree[2 * pos + 1]);
 
}
int main()
{ 
    ios_base::sync_with_stdio(false);
    int q;
    cin >> n >> q;
    for(int i = 0; i < n; i++) {
      cin >> a[i];
    }
    build(0, n - 1, 1);
    
    
    while(q--) {
      int a, b;
      cin >> a >> b;
      a--; 
      update(0, n - 1, 1, a, b);
      ll res = query(0, n - 1, 1, 0, n - 1).max_sum;
      if(res < 0) {
        res = 0;
      }
    cout << res  << endl;
    }
      return 0;
}