Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() (int, error) {
	n, err := strconv.Atoi(nextString())
	return n, err
}

func main() {
	scanner.Split(bufio.ScanWords)

	stack := []int{}
	for {
		n, err := nextInt()
		if err != nil {
			break
		}

		if n == 0 { // pop
			fmt.Println(stack[len(stack)-1])
			stack = stack[0:(len(stack) - 1)]
		} else { // push
			stack = append(stack, n)
		}
	}
}

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

#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,s,n) for(int i=(s);i<=(n);i++)
#define repr(i,n) for(int i=n-1;i>=0;i--)
#define REPR(i,s,n) for(int i=(s);i>=(n);i--)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define Eunique(v) v.erase(unique(all(v)),v.end())
#define Eback(s) s.erase(s.end()-1,s.end())
#define rev(v) reverse(all(v))
#define minvec(v) *min_element(all(v))
#define maxvec(v) *max_element(all(v))
#define sumvec(v) accumulate(all(v),0LL)
#define mapmin(v) v.rbegin()->first
#define mapmax(v) v.begin()->first
#define pb push_back
#define pf push_front
#define m_p make_pair
#define DOUBLE fixed << setprecision(15)
#define OK cerr<<"OK\n"
#define OK1 cerr<<"OK1\n"
#define OK2 cerr<<"OK2\n"
#define sz(s) (long long)s.size()
#define INF ((1LL<<62)-(1LL<<31))
#define zero(x,n) setw(x) << setfill('0') << n
#define endl '\n'

typedef long long ll;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long long> vll;
typedef vector<vll> vvll;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<string> vs;

typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<pair<int,int>> vpii;
typedef vector<pair<ll,ll>> vpll;

const double pi = acos(-1.0);
const ll mod=1000000007;
const ll mod2=998244353;

template<class A, class B>
ostream& operator<<(ostream& ost, const pair<A, B>&p) {
	ost << "{" << p.first << ", " << p.second << "} ";
	return ost;
}

template<class T>
ostream& operator<<(ostream& ost, const vector<T>&v) {
	ost << "{";
	for (int i = 0; i<(int)v.size(); i++) {
		if (i)ost << " ";
		ost << v[i];
	}
	ost << "} \n";
	return ost;
}

template<class A, class B>
ostream& operator<<(ostream& ost, const map<A, B>&v) {
	ost << "{";
	for (auto p:v) {
		ost << "{" << p.first << ", " << p.second << "} ";
	}
	ost << "} ";
	return ost;
}

void out(){cout << "\n";}
template<class T,class... Args>
void out(const T &x,const Args &... args){
	cout << x << " ";
	out(args...);
}

template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
	for(T& e: vec) is >> e;
	return is;
}

template<typename T>
string join(vector<T>& vec, string sep=" "){
	stringstream ss;
	for(int i=0;i<(int)vec.size();i++){
		ss << vec[i] << (i+1==(int)vec.size()?"\n":sep);
	}
	return ss.str();
}

template<class T>
inline bool chmax(T& a, T b){if(a<b){a=b;return true;} return false;}

template<class T>
inline bool chmin(T& a, T b){if(a>b){a=b;return true;} return false;}

void YES(bool b) {cout << ((b)?"YES\n":"NO\n");}
void Yes(bool b) {cout << ((b)?"Yes\n":"No\n");}
void yes(bool b) {cout << ((b)?"yes\n":"no\n");}
void Yay(bool b) {cout << ((b)?"Yay!\n":":(\n");}

ll powmod(ll a,ll b){ll c=1; while(b>0){ if(b&1){ c=a*c%mod; } a=a*a%mod; b>>=1; } return c;}
ll nCrmod(ll n,ll r){ll x=1,y=1; for(ll i=0;i<r;i++) {x=x*(n-i)%mod; y=y*(i+1)%mod; } return x*powmod(y,mod-2)%mod;}
ll gcd(ll x, ll y) {return __gcd(x,y);}
ll lcm(ll x, ll y) {return x/__gcd(x,y)*y;}

int main()
{
	stack<ll> s;
	ll x;
	while(cin >> x){
		if(x==0){
			cout << s.top() << endl;
			s.pop();
		}
		else s.push(x);
	}
	return 0;
}

C++: #include <iostream>
#include <stack>
using namespace std;

int main(){
	stack<int> st;
	int n, a;

	while(cin >> n){
		if(n!=0){
			st.push( n );
		}else{
			a = st.top();
			cout << a << endl;
			st.pop();
		}
	}
}

C++: #include <iostream>
#include <stack>

using namespace std;

int main() {
	int n;
	stack<int> s;
	while (cin >> n) {
		if (n == 0) {
			cout << s.top() << endl;
			s.pop();
		}
		else {
			s.push(n);
		}
	}
	return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <sstream>
#include <stdio.h>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <math.h>
#include <utility>
#include <string>
#include <ctype.h>
#include <cstring>
#include <cstdio>
#include <sstream>
using namespace std;

#define FOR(i,k,n) for(int i = (k); i < (n); i++)
#define REP(i,n) FOR(i,0,n)
#define INF 114514810
#define ll long long
//#define scanf scanf_s

int main()
{
	vector<int> v;
	int a;
	while (cin >> a) 
	{
		if (a != 0) v.push_back(a);
		else
		{
			cout << v.back() << endl;
			v.pop_back();
		}

	}
	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
using namespace std;
static const double EPS = 1e-5;
typedef long long ll;
#define FOR(i,n) for(i=0;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)

int main(){
	stack<int> st;
	for(int i;cin>>i;){
		if(i)st.push(i);
		else{cout<<st.top()<<endl;st.pop();}
	}
	return 0;
}

C++: #include <iostream>
#include <stack>

int main(){

	std::stack<int> train;

	int buf;

	while(std::cin >> buf){

		if(buf == 0){

			std::cout << train.top() << std::endl;
			train.pop();

		}else{

			train.push(buf);

		}
	
	}

	return 0;
}

C++: #include <iostream>
using namespace std;

int main() {
  int order,i;
  int syako[1000];
  i=0;
  while(cin >> order) {
    if(order != 0) {
      syako[i] = order;
      i++;
    }
    else {
      cout << syako[i-1] << endl;
      i--;
    }
  }
}

C++: #include<stack>
#include<iostream>

using namespace std;

int main()
{
	stack<int> in,out;
	int i;
	while(cin>>i){
		if(i)	in.push(i);
		else	out.push(in.top()),in.pop();
	}
	while(!out.empty())	in.push(out.top()),out.pop();	// reverse
	while(!in.empty()){
		printf("%d\n",in.top());
		in.pop();
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
using namespace std;
int main()
{
	vector<int> garage;
	vector<int> outgoing;
	int data;
	int train;
	while(cin>>train)
	{
		if(0==train)
		{
			outgoing.push_back(garage.back());
			garage.pop_back();
		}
		else
		{
			garage.push_back(train);
		}
	}
	for(int i=0;i<outgoing.size();++i)
	{
		cout<<outgoing[i]<<endl;
	}
}

C++: #include <iostream>
#include <stack>
using namespace std;

int main()
{
	stack<int> s;
	deque<int> ans;
	int n;

	while (cin >> n)
	{
		if (cin.eof()) return 0;
		if (n == 0)
		{
			ans.push_front(s.top());
			s.pop();
			//if (s.empty()) break;
		}
		else
		{
			s.push(n);
		}
	}

	while (1)
	{
		if (!ans.empty())
		{
			cout << ans.back() << endl;
			ans.pop_back();
		}
		else break;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <stack>
#include <math.h>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <vector>

using namespace std;






int main()
{
	int a;
	stack<int> s;
	while (cin >> a) {
		s.push(a);
		if (s.top() == 0) {
			s.pop();
			cout << s.top() << endl;
			s.pop();
		}
	}
}