#include<bits/stdc++.h>
#include <string.h>
using namespace std;
struct node{
	string a;
}s1[500010];
string s,t;
int top,q[500010],lt[500010];
int main(){
	freopen("extract.in","r",stdin);
	freopen("extract.out","w",stdout);
	cin>>s;
	for(int i=0;i<=s.size()-1;i++){
		if(s[i]=='['){
			q[top+1]=0;
			s1[top+1].a="";
			top++;
		}
		else if(s[i]==']'){
			for(int i=1;i<=q[top];i++){
				s1[top-1].a+=s1[top].a;
			}
			top--;
		}
		else{
			if('0'<=s[i]&&s[i]<='9'){
				q[top]=q[top]*10+s[i]-'0';
			}
			else{
				s1[top].a+=s[i];
			}
		}
	}
	cout<<s1[0].a;
	return 0;
}