/*
#include <stdio.h>
#define SIZE 50
//Last In First Out 후입선출
int stack[SIZE];
int top=-1; //마지막으로 입력된 데이터의 위치
void push(int data)
{
//full check
if(top==SIZE-1) return ;
stack[++top]=data;
}
int pop()
{
//empty check 스택이 비어있을때, 더이상 pop 못하게 처리
if(top==-1) return -1000;
return stack[top--];
}
void view()
{
printf("stack [ ");
for(int i=0;i<=top;i++)
printf("%d ",stack[i]);
printf("]\n");
}
int main()
{
push(3);
view();
push(4);
view();
printf("%d\n",pop());
view();
pop();
view();
pop();
view();
return 0;
}
*/
//2016
//3117
//3129
//3021
/*
#include<stdio.h>
#define SIZE 200
int stack [SIZE];
int top=-1 ;
void push(int data)
{
stack[++top]=data;
}
int pop()
{
return stack[top--];
}
int main()
{
int a;
char str[201];
scanf("%d %s", &a, str);
for(int i=a-1;i>=0;i--)
{
push(str[i]-'0');
}
while(top!=-1) //stack 내용물 모두 pop
{
printf("%d",pop());
if(top%3==2)
{
printf(",");
}
}
return 0;
}
*/
/*
#include <stdio.h>
#define SIZE 100001
int stack[SIZE];
int top=-1;
void push(int data)
{
stack[++top]=data;
}
int pop()
{
return stack[--top];
}
int main()
{
int k,i,n,sum=0;
scanf("%d",&n);
for(i=1;i<=n;i++)
{
scanf("%d",&k);
if(k==0)
{
pop();
}
else
{
push(k);
}
}
while(top!=-1)
{
sum+=pop();
}
printf("%d",sum);
return 0;
}
*/