Language: C++

#include <bits/stdc++.h>
using namespace std;
/*#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T> using gpp_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename L> using gpp_map = tree<T, L, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using gpp_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;*/
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define bit_exist(x, n) ((x >> n) & 1)
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define Return(ans) { cout << (ans) << endl; return 0; }
#define pb push_back
#define f first
#define s second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void Ans(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using PiP = pair<int, Pii>;
using PPi = pair<Pii, int>;
using Pdi = pair<double, int>;
using bools = vector<bool>;
using pairs = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

const int mod = 1000000007;
//const int mod = 998244353;
//#define Add(x, y) x = (x + (y)) % mod
//#define Mult(x, y) x = (x * (y)) % mod

vec calcv1(int x0, int K){
    vec vx;
    while(x0 <= -K){
        vx.pb(-K); x0 += K;
    }
    while(x0 >= K){
        vx.pb(K); x0 -= K;
    }
    if(x0 > 0){
        if((x0 - K) % 2 == 0) vx.pb(x0);
        else{
            vx.pb(K); vx.pb(x0 - K);
        }
    }else if(x0 < 0){
        if((x0 - K) % 2 == 0) vx.pb(x0);
        else{
            vx.pb(-K); vx.pb(x0 + K);
        }
    }
    return vx;
}

vec calcv2(int x0, int K){
    vec vx;
    while(x0 <= -K){
        vx.pb(-K); x0 += K;
    }
    while(x0 >= K){
        vx.pb(K); x0 -= K;
    }
    if(x0 > 0){
        vx.pb(K); vx.pb(x0 - K);
    }else if(x0 < 0){
        vx.pb(-K); vx.pb(x0 + K);
    }else vx.pb(0);

    return vx;
}


pairs combine(vec vx, vec vy, int K){
    assert(SZ(vx) % 2 == SZ(vy) % 2);
    Reverse(vx), Reverse(vy);
    while(SZ(vx) < SZ(vy)){ vx.pb(K); vx.pb(-K); }
    while(SZ(vy) < SZ(vx)){ vy.pb(K); vy.pb(-K); }
    int N = SZ(vx);

    int nx = 0, ny = 0;
    REP(i, N) if(llabs(vx[i]) == K) nx++;
    REP(i, N) if(llabs(vy[i]) == K) ny++;
    
    while(nx + ny < N){
        vx.pb(K); vx.pb(-K);
        vy.pb(K); vy.pb(-K);
        nx += 2;
        ny += 2;
        N += 2;
    }

    pairs ans(N);
    Reverse(vx);
    int x = 0, y = 0;
    REP(i, N){
        x += (vx[i] + vy[i]) / 2;
        y += (vx[i] - vy[i]) / 2;
        ans[i] = Pii(x, y);
    }
    return ans;
}

signed main(){

    int K, X, Y; cin >> K >> X >> Y;
    int x = X + Y, y = X - Y;

    if(x % 2 == 1 && K % 2 == 0){
        Return(-1);
    }

    pairs ans;
    if(K % 2 == 1){
        vec vx = calcv1(x, K), vy = calcv1(y, K);
        ans = combine(vx, vy, K);
    }else{
        //assert(false);
        int M = INF;
        REP(t, 2) REP(u, 2){
            vec vx, vy;
            if(t == 0) vx = calcv1(x, K);
            else vx = calcv2(x, K);
            if(u == 0) vy = calcv1(y, K);
            else vy = calcv2(y, K);

            //vdebug(vx); vdebug(vy);

            if(SZ(vx) % 2 == SZ(vy) % 2){
                pairs tmp = combine(vx, vy, K);
                if(SZ(tmp) < M){
                    M = SZ(tmp);
                    ans = tmp;
                }
            }
        }
    }
    assert(M < INF);

    Out(SZ(ans));
    for(auto q: ans) cout << q.f << " " << q.s << endl;

    return 0;
}


Compiler output:
In file included from /usr/include/c++/14/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:106,
                 from a.cc:1:
a.cc: In function 'int main()':
a.cc:161:12: error: 'M' was not declared in this scope
  161 |     assert(M < INF);
      |            ^