sgu 179 Brackets light

#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cstring>
#include <map>
#include <queue>
#include <set>
#include <cassert>
#define mkp make_pair
using namespace std;
const double EPS=1e-8;
const int SZ=800010,INF=0x7FFFFFFF;
typedef long long lon;

string work(string str)
{
    int i;
    int num1=0,num2=1;
    for(i=str.size()-2;i>=0;i-=2)
    {
        if(!(str[i]==‘(‘&&str[i+1]==‘)‘))break;
        num1+=2;
    }
    
    if(i<0)return "";
    for(;!(str[i]==‘(‘&&str[i+1]==‘)‘);--i,++num2);
    //cout<<i<<" "<<num2<<endl;
    string res="";
    if(num1==0)
    {
        string tmp(str.begin(),str.begin()+str.size()-num2-1);
        tmp+=")(";
        string tmp2(str.begin()+str.size()-num2+1,str.end());
        res=tmp+tmp2;
    }
    else
    {
        if(num2!=2)
        {
            string tmp(str.begin(),str.begin()+str.size()-num2-num1-1);
            tmp+=")(";
            tmp+=string(num1/2,‘(‘)+string(num1/2,‘)‘);
            string tmp2(str.begin()+str.size()-num2-num1+1,str.end()-num1);
            res=tmp+tmp2;
        }
        else
        {
            string tmp(str.begin(),str.begin()+str.size()-num2-num1-1);
            tmp+=")";
            string tmp2((num1+num2)/2,‘(‘);
            res=tmp+tmp2+string((num1+num2)/2,‘)‘);
        }
    }
    return res;
}

int main()
{
    std::ios::sync_with_stdio(0);
    //freopen("d:\\1.txt","r",stdin);
    lon casenum=INF;
    string str;
    //cin>>casenum;
    //for(lon time=1;time<=casenum;++time)
    {
        cin>>str;
        str=work(str);
        if(str=="")cout<<"No solution"<<endl;
        else cout<<str<<endl;
    }
    return 0;
}