#include <iostream>
using namespace std;
int hammingDistance(string a, string b) {
int distance = 0;
for (int i = 0; i < a.length(); i++) {
if (a[i] != b[i]) {
distance++;
}
}
return distance;
}
int main() {
string a = "karolin";
string b = "kerstin";
int distance = hammingDistance(a, b);
cout << distance << endl;
return 0;
}