Buggy python submission (verdict: Runtime Error):
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpl;
typedef vector<vi> vvi;
typedef vector<vll> vvll;

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
void __print(vector<bool> v) {bool first = true; cerr << "{"; for (int i = 0; i < static_cast<int>(v.size()); i++) {if (!first) {cerr << ", ";} first = false; __print(v[i]);} cerr << "}";}
template <size_t N>
void __print(bitset<N> bs) {string res = "<"; for (size_t i = 0; i < N; i++) {res += static_cast<char>('0' + bs[i]);} res += '>'; cerr << res;}
template<typename T>
void __print(const T &x) {int j = 0; cerr << "{"; for (auto &i: x) cerr << (j++ ? ", " : ""), __print(i); cerr << "}";}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << "("; __print(x.first); cerr << ", "; __print(x.second); cerr << ")";}
template <typename A, typename B, typename C>
void __print(const tuple<A, B, C> t) {cerr << "("; __print(get<0>(t)); cerr << ", "; __print(get<1>(t)); cerr << ", "; __print(get<2>(t)); cerr << ")";}
template <typename A, typename B, typename C, typename D>
void __print(const tuple<A, B, C, D> t) {cerr << "("; __print(get<0>(t)); cerr << ", "; __print(get<1>(t)); cerr << ", "; __print(get<2>(t)); cerr << ", "; __print(get<3>(t)); cerr << ")";}
void _print() {cerr << " ]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}

#ifndef ONLINE_JUDGE
#define deb(...) cerr << "~ [ " << #__VA_ARGS__ << " ] => [ "; _print(__VA_ARGS__)
#define debn(...) cerr << "~ [ "; _print(__VA_ARGS__)
#else
#define deb(...)
#define debn(...)
#endif

#define ALL(DS) (DS).begin(), (DS).end()
#define PB push_back
#define EB emplace_back
#define SZ(DS) (int)((DS).size())
#define fo(ITER, LO, UP) for (ITER = (LO); ITER < (UP); ++ITER)
#define foi(ITER, LO, UP) for (int ITER = (LO); ITER < (UP); ++ITER)
#define foll(ITER, LO, UP) for (ITER = (ll)(LO); ITER < (ll)(UP); ++ITER)
#define folli(ITER, LO, UP) for (ll ITER = (ll)(LO); ITER < (ll)(UP); ++ITER)
#define iter(ITER, DS) for (auto &ITER: DS)

const int M = 1000000007;
const int INF = 1e9 + 5;

void init() {}

void solve() {
    int a, b, c, d; cin >> a >> b >> c >> d;
    
    cout << max({a*c, a*d, b*c, b*d}) << "\n";
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.setf(ios::fixed); cout.precision(20);
    init();
    solve();
}



Fixed submission:
a, b, c, d = [int(x) for x in input().split()]
print(max(a*c, a*d, b*c, b*d))