decodif

#include <iostream>
#include <stack>
using namespace std;
string str;

string decode(string str)
{
    stack<int> integerstack;
    stack<char> stringstack;
    string temp="",result="";
    for(unsigned i=0;i<str.length();++i)
    {
        int cnt=0;
        if(str[i]>='0'&&str[i]<='9')
        {
            while(str[i]>='0'&&str[i]<='9')
                cnt=cnt*10+str[i]-'0',++i;
            --i;
            integerstack.push(cnt);
        }
        else
            if(str[i]==']')
            {
                temp="";
                cnt=0;
                if (! integerstack.empty())
                {
                    cnt = integerstack.top();
                    integerstack.pop();
                }
                while(!stringstack.empty()&&stringstack.top()!='[')
                    temp=stringstack.top()+temp,stringstack.pop();
                if(!stringstack.empty()&&stringstack.top()=='[')
                    stringstack.pop();
                for(int j=0;j<cnt;++j)
                    result=result+temp;
                for(unsigned j=0;j<result.length();++j)
                    stringstack.push(result[j]);
                result="";
            }
            else
                if(str[i]=='[')
                {
                    if(str[i-1]>='0'&&str[i-1]<='9')
                        stringstack.push(str[i]);
                    else
                        stringstack.push(str[i]),integerstack.push(1);
                }
                else
                    stringstack.push(str[i]);
    }
    while(!stringstack.empty())
        result=stringstack.top()+result,stringstack.pop();
    return result;
}

int main()
{
    cin>>str;
    cout<<decode(str)<<'\n';
    return 0;
}