Language: C++

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

#define REP(i,m,n) for(int i=(m); i<(int)(n); i++)
#define RREP(i,m,n) for(int i=(int)(n-1); i>=m; i--)
#define rep(i,n) REP(i,0,n)
#define rrep(i,n) RREP(i,0,n)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define fi first
#define se second
#define debug(...) {cerr<<"[L"<<__LINE__<<"] "; _debug(__VA_ARGS__);}

template<typename T>
string join(const vector<T>&v, string del=", "){ stringstream s;
    for(auto x : v) s << del << x; return s.str().substr(del.size());
}
template<typename T>
ostream& operator<<(ostream& o, const vector<T>&v){
    if(v.size()) o << "[" << join(v) << "]"; return o;
}
template<typename T>
ostream& operator<<(ostream& o, const vector<vector<T> >&vv){
    int l = vv.size();
    if(l){ o<<endl; rep(i,l) o << (i==0 ? "[ " : ",\n  " ) << vv[i] << (i==l-1 ? " ]" : ""); }
    return o;
}
template<typename T1, typename T2>
ostream& operator<<(ostream& o, const pair<T1, T2>& p){
    return o << "(" << p.first << ", " << p.second << ")";
}
inline void _debug(){cerr<<endl;}
template<class First, class... Rest>
void _debug(const First& first, const Rest&... rest){cerr<<first<<" ";_debug(rest...);}

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;

const double PI = (1*acos(0.0));
const double EPS = 1e-9;
const int INF = 0x3f3f3f3f;
const ll INFL = 0x3f3f3f3f3f3f3f3fLL;
const ll mod = 1e9 + 7;

inline void finput(string filename) {
    freopen(filename.c_str(), "r", stdin);
}

int main(){
    ios_base::sync_with_stdio(0);
    // finput("./input");
    int n,k; cin >> n >> k;
    vl P, M;
    rep(i,n){
        ll a; cin >> a;
        if(a >= 0) P.push_back(a);
        else M.push_back(-a);
    }
    if(k == n){
        ll ans = 1;
        rep(i,P.size()){
            ans *= P[i];
            ans %= mod;
        }
        rep(i,M.size()){
            ans *= mod - M[i];
            ans %= mod;
        }
        cout << ans << endl;
        return 0;
    }
    if(k & 1 && P.size() == 0){
        sort(all(M));
        ll ans = 1;
        rep(i,k){
            ans *= mod - M[i];
            ans %= mod;
        }
        cout << ans << endl;
        return 0;
    }
    P.push_back(1);
    sort(rall(P));
    sort(rall(M));

    ll i = 0, j = 0;
    ll ans = 1;
    while(k > i + j){
        if(i + j == k-1){
            ans *= P[i];
            ans %= mod;
            i += 1;
        }else{
            ll p = -INFL, m = -INFL;
            if(i <= P.size()-1) p = P[i]; if(i+1 <= P.size()-1) p *= P[i+1];
            if(i <= M.size()-1) m = M[i]; if(i+1 <= M.size()-1) m *= M[i+1];

            if(i == P.size()-1 || m >= p){
                ans *= m;
                ans %= mod;
                j += 2;
            }else{
                ans *= P[i];
                ans %= mod;
                i += 1;
            }
        }
    }
    cout << ans << endl;
    return 0;

Compiler output:
a.cc: In function 'int main()':
a.cc:115:14: error: expected '}' at end of input
  115 |     return 0;
      |              ^
a.cc:54:11: note: to match this '{'
   54 | int main(){
      |           ^