Converting string and int for using stringstream
 #include<bits/stdc++.h>  using namespace std;  #define ll long long    string int_to_str(int n)  {      stringstream ss;      ss<<n;      return ss.str();  }   int str_to_int(string s)  {      stringstream ss(s);      int n;      ss>>n;      return n;  }  int main()  {      ios_base::sync_with_stdio(0);      string s;      cout<<"Input string : ";      cin>>s;      int n;      cout<<"Input integer : ";      cin>>n;      int m=str_to_int(s);      string p=int_to_str(n);      cout<<"String to integer convert: "<<m<<endl;      cout<<"Integer to string convert: "<<p<<endl;  }