/* 2. ´ÙÀ½ ÇÁ·Î±×·¥ÀÇ Ãâ·ÂÀ» ½á¶ó. */

#include <stdio.h>
#include <string.h>
class Stack {
	int i;
	int top;
	int x[100];
public:
	Stack();
	void push(int a);
	int pop();
	void print();
};
Stack::Stack() {
	i = 0; top = 0; 
}
void Stack::push(int a) {
	for (int index = 0; index < a; index++) {
		x[top] = i;
		top++;
	}
	if (a > 0) i++;
}
int Stack::pop() {
	top = 9;
	return x[top];
}
void Stack::print() {
	for (int index = 0; index <= top; index++) {
		printf("%d",x[index]);
	}
}
void main()
{
	char number[10];

	Stack aStack;
	strcpy(number,"2011810");
	for(int i = 0; i < 7; i++) {
		aStack.push(number[i]-'0');
	}
	aStack.pop();
	aStack.print();
}