Mayor que la salida de un conformación sin signo de n bits 10-bit n-1

#include<iostream>
#include<cmath>
using namespace std;
unsigned fun(unsigned integ)
{
 int b,count=0;
 b=integ;
 while(integ!=0)
 {
  integ=integ/10;
  count++;
 }
 cout<<round(b/pow(10,count-2))-10*(round(b/pow(10,count-1)));
}
int main()
{
 unsigned n=0;
 cin>>n;
 fun(n);
}