Concurrence_lock_error

[srivastava.samriddhi99 (Samriddhi Srivastava)]

I am getting this error while trying to print t. Please explain this.

#include
#include
using namespace std;
int main() {
string s;
cin>>s;
string t;
t=s[0]+"\0";
cout<<s<<endl<<t;
return 0;
}