#include <iostream>
#include <string>
using namespace std;
 
const int a = 4; 
const int b = 3; 
 
string to_bits(int a)
{
	string res="";
	for(;a!=0;a=a>>1) res = ((a&1)==1?"1":"0") + res; 
	return res;
}
 
unsigned int num_bits(const int a, const int b)
{
	unsigned int res=0;
	auto c = a ^ b; 
 
	for(auto c=a^b; c!=0; c=c >> 1) res += ( (c&1)==1?1:0 ); 
 
	return res; 
}
 
int main() {
	// your code goes here
	cout << "a=" << a <<" = " << to_bits(a) << ", b=" << b << " = " << to_bits(b) << " --> " << num_bits(a, b) << endl; 
	return 0;
}
 
 

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