Go: package main

import "fmt"

func main() {
	var i int
	stack := make([]int, 0)
	for {
		v, _ := fmt.Scan(&i)
		// fmt.Println(stack)
		// println(v)
		if v == 0 {
			break
		}
		if i == 0 {
			fmt.Println(stack[len(stack)-1])
			stack = stack[:len(stack)-1]
			continue
		}
		stack = append(stack, i)
	}
}

C++: #define _USE_MATH_DEFINES
#include<iostream>
#include<string>
#include<queue>
#include<cmath>
#include<map>
#include<set>
#include<list>
#include<iomanip>
#include<vector>
#include<random>
#include<functional>
#include<algorithm>
#include<stack>
#include<cstdio>
#include<bitset>
#include<unordered_map>
#include<climits>
#include<fstream>
using namespace std;
///////////////////library zone!!!!!!!!!!!!!!!!!!!!!!!!!!!!
typedef long long ll;
typedef long double ld;
#define all(a) (a).begin(),(a).end()
#define EPS (1e-5)
const ll Mod = 1000000007;
const ll mod = 998244353;
struct H {
	ll x, y;
	bool operator<(const H &b) const {
		if (x != b.x) return x < b.x;
		return y < b.y;
	}
	bool operator>(const H &b) const {
		if (x != b.x) return x > b.x;
		return y > b.y;
	}
	bool operator==(const H &b) const { return x == b.x&&y == b.y; }
	bool operator!=(const H &b) const { return (*this) != b; }
};
struct P {
	ll pos, cost;
	bool operator<(const P &b) const { return cost < b.cost; }
	bool operator>(const P &b) const { return cost > b.cost; }
};
struct B {
	ll to, cost;
};
struct E {
	ll from, to, cost;
	bool operator<(const E &b) const { return cost < b.cost; }
	bool operator>(const E &b) const { return cost > b.cost; }
};
template<typename T, typename U>
void chmin(T &a, U b) {
	if (a > b) a = b;
}
template<typename T, typename U>
void chmax(T &a, U b) {
	if (a < b) a = b;
}
template<typename T>
T max_0(T a) {
	if (a < 0) return 0;
	return a;
}
template<typename T>
T min_0(T a) {
	if (a > 0) return 0;
	return a;
}
ll read() {
	ll u;
	ll k = scanf("%lld", &u);
	return u;
}
ll gcd(ll i, ll j) {
	if (i > j) swap(i, j);
	if (i == 0) return j;
	return gcd(j%i, i);
}
ll mod_pow(ll x, ll n, ll p) {
	ll res = 1;
	while (n > 0) {
		if (n & 1) res = res * x % p;
		x = x * x % p;
		n >>= 1;
	}
	return res;
}//x^n%p
const ll Inf = 3023372036854775807;
const int inf = 1500000000;
#define int long long
//----------------------------------------------------
class Vec2 {
public:
	ld x, y;
	Vec2() { x = 0, y = 0; }
	Vec2(ld x, ld y) :x(x), y(y) {}
	ld length() {
		return sqrt(x*x + y * y);
	}
	void normal() {
		ld len = this->length();
		if (len == 0) return;
		x /= len, y /= len;
	}
	Vec2 operator+(Vec2 vec) {
		return Vec2(x + vec.x, y + vec.y);
	}
	Vec2 operator-(Vec2 vec) {
		return Vec2(x - vec.x, y - vec.y);
	}
	Vec2 operator*(int cons) {
		return Vec2(x*cons, y*cons);
	}
	ld operator*(Vec2 vec) {
		return x * vec.x + y * vec.y;
	}
	ld operator%(Vec2 vec) {
		return x * vec.y - y * vec.x;
	}
};
ld dot(Vec2 a, Vec2 b) {
	return a.x*b.x + a.y*b.y;
}
ld cross(Vec2 a, Vec2 b) {
	return a.x*b.y - a.y*b.x;
}
ld areaIntegral(Vec2 a, Vec2 b) {
	return abs(a.x*b.y - a.y*b.x) / 2.0;
}
class Vec3 {
public:
	ld x, y, z;
	Vec3() { x = 0, y = 0, z = 0; }
	Vec3(ld x, ld y, ld z) :x(x), y(y), z(z) {}
	ld length() {
		return sqrt(x*x + y * y + z * z);
	}
	void normal() {
		ld len = this->length();
		if (len == 0) return;
		x /= len, y /= len, z /= len;
	}
	Vec3 operator+(Vec3 vec) {
		return Vec3(x + vec.x, y + vec.y, z + vec.z);
	}
	Vec3 operator-(Vec3 vec) {
		return Vec3(x - vec.x, y - vec.y, z - vec.z);
	}
	Vec3 operator*(int cons) {
		return Vec3(x*cons, y*cons, z*cons);
	}
	ld operator*(Vec3 vec) {
		return x * vec.x + y * vec.y + z * vec.z;
	}
};
ld dot(Vec3 a, Vec3 b) {
	return a.x*b.x + a.y*b.y + a.z*b.z;
}
class Line {
public:
	Vec2 from, to;
	Line(Vec2 from, Vec2 to) :from(from), to(to) {}
};
Line getPerpendicularBisector(Line line) {
	int cx = (line.from.x + line.to.x) / 2, cy = (line.from.y + line.to.y) / 2;
	Vec2 p = Vec2(cx + (line.from.y - line.to.y), cy + (line.to.x - line.from.x));
	return Line(Vec2(cx, cy), p);
}
signed main() {
	int n;
	stack<int>st;
	while (cin >> n) {
		if (n) {
			st.push(n);
		}
		else {
			cout << st.top() << endl;
			st.pop();
		}
	}
}

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

int main()
{
    int train[10]={0},n,count=0,outTrain[10],trainCount=0;
    while(scanf("%d",&n)!=EOF){
        if(n){
            for(int i=count ; i!=0 ; i--){
                train[i]=train[i-1];
            }
            train[0]=n;
            count++;
        }
        else{
            outTrain[trainCount]=train[0];
            for(int i=0 ; i<count ; i++){
                train[i]=train[i+1];
            }
            train[count]=0;
            count--;
            trainCount++;
        }
    }
    for(int i=0 ; i<trainCount ; i++){
        cout << outTrain[i] << '\n';
    }
    return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <queue>
#include <cstring>
#include <functional>
#include <stack>

using namespace std;

#define REP(i,a,b) for((i)=(a);(i)<(int)(b);(i)++)
#define rep(i,n) REP(i,0,n)
// BEGIN CUT HERE
#define foreach(itr,c) for(typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
template<class T> inline string toString(T x){ostringstream sout;sout<<x;return sout.str();}
// END CUT HERE

int main(){
  int in;
  stack<int> s;

  while(scanf("%d", &in) != EOF){
    if(in == 0){
      printf("%d\n",s.top());
      s.pop();
    }
    else s.push(in);
  }

  return 0;
}

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

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

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

using namespace std;

int main() {
	stack<int> st;
	int a,i;
	for (i = 0; i < 100; i++) {
		cin >> a;
		if (a == 0) {
			cout << st.top()<<endl;
			st.pop();
		}
		else {
			st.push(a);
		}
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cctype>
#include <cstdio>
#include <math.h>
using namespace std;

int main() {
	
	int c[256],e[256],m,n=0,k=0;
	for(int i=0;i<10;i++){c[i]=0;e[i]=0;}
	
	while(cin>>m){
		if(m==0){e[k]=c[n-1];k++;c[n-1]=0;n--;}
		else {c[n]=m;n++;}
	}
	
	for(int i=0;i<k;i++)cout<<e[i]<<endl;
	
	return 0;
}

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

using namespace std;

int main(){
	stack<int> train;
	int n;
	while(cin>>n){
		if(n==0){
			cout<<train.top()<<endl;
			train.pop();
		}else{
			train.push(n);
		}
	}
	while(1);
	return 0;
}

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

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

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

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

int main(){
	int n;
	stack<int> stk;
	queue<int> que;
	while(cin>>n){
		if(n==0){
			que.push(stk.top());
			stk.pop();
		}else{
			stk.push(n);
		}
	}
	while(!que.empty()){
		cout<<que.front()<<endl;
		que.pop();
	}
	return 0;
}

C++: //#define scanf_s scanf
#include <stdio.h>
#include <string>
#include <iostream>
#include <math.h>
using namespace std;
#define MAX 100
int main(void)
{
	int n, now = 0;
	int list[MAX] = { 0 };
	do{
		scanf_s("%d", &n);
		if (n != 0) { list[now] = n; ++now; }
		else { --now; printf("%d\n", list[now]); }
	} while (now != 0);
}

C++: #include <stdio.h>
#include <stack>

using namespace std;

int main()
{
	stack<int> sta;
	int num;
	while(scanf("%d", &num) != EOF){
		if(num == 0 && sta.empty() == 0){
			printf("%d\n",sta.top());
			sta.pop();
		}else{
			sta.push(num);
		}
	}
	return 0;
}