Recurrsion codes of string

https://hack.codingblocks.com/contests/c/512/346
output is
#include
#include<string.h>
using namespace std;
void recurrsioncodes(string str,string osf)
{
if((str.size())==0)
{
cout<<osf<<" “;
return;
}
int ch=str[0]-‘0’;
int ch1=str[1]-‘0’;
int d=ch+96;
int e=(10*ch)+ch1+96;
char e1;
char a;
a=d;
e1=e;
// cout<<d<<” "<<e<<endl;
recurrsioncodes(str.substr(1),osf+a);

recurrsioncodes(str.substr(2),osf+e1);

}
int main()
{
string str;
cin>>str;
recurrsioncodes(str,"");
}
i dont know why the recurrsion is terminating

please find the error