#include <bits/stdc++.h>
using namespace std;

signed main() {
  ios::sync_with_stdio(false);

  int64_t D;
  int Q;
  cin >> D >> Q;

  vector<int64_t> A(Q), B(Q);
  for (int i = 0; i < Q; ++i) {
    cin >> A[i] >> B[i];
  }

  vector<int64_t> pnts;
  map<int64_t, int> mp;
  for (int i = 0; i < Q; ++i) {
    pnts.emplace_back(A[i]);
    pnts.emplace_back(B[i] + 1);
  }
  sort(pnts.begin(), pnts.end());
  pnts.erase(unique(pnts.begin(), pnts.end()), pnts.end());
  for (int i = 0; i < pnts.size(); ++i) {
    mp[pnts[i]] = i;
  }

  int BS = sqrt(pnts.size());
  vector<int> cnt(pnts.size()), bcov((pnts.size() + BS - 1) / BS), bcnt((pnts.size() + BS - 1) / BS);
  for (int qi = 0; qi < Q; ++qi) {
    int x = mp[A[qi]];
    int y = mp[B[qi] + 1];
    while (x % BS > 0 && x < y) {
      if (cnt[x] == 0) {
        cnt[x] = 1;
        if (++bcnt[x / BS] == BS) {
          bcov[x / BS] = 1;
        }
      }
      ++x;
    }
    while (x / BS != y / BS) bcov[x++ / BS] = 1;
    while (x < y) {
      if (cnt[x] == 0) {
        cnt[x] = 1;
        if (++bcnt[x / BS] == BS) {
          bcov[x / BS] = 1;
        }
      }
      ++x;
    }
    int64_t ans = 0;
    for (int i = 0; i < pnts.size(); ++i) {
      if (cnt[i] || bcov[i / BS]) {
        int j = i + 1;
        while (j < pnts.size()) {
          if (bcov[j / BS]) {
            j = (j + BS) / BS * BS;
          } else if (cnt[j]) {
            ++j;
          } else {
            break;
          }
        }
        if (j >= pnts.size()) {
          ans = max(ans, D - pnts[i]);
        } else {
          ans = max(ans, pnts[j] - pnts[i]);
        }
        i = j;
      } else if (bcnt[i / BS] == 0) {
        i = (i + BS) / BS * BS - 1;
      }
    }
    cout << ans << endl;
  }

  return 0;
}