//异或问题
#include <iostream>
#include<string>
#include <math.h>
using namespace std;
int main(int argc, const char * argv[]) {
int n;
string a,b;
cin>>n;
cin>>a>>b;
int Count=0;
for (int i=0; i<n; i++) {
if (a[i]!=b[i])
Count+=pow(2,n-i-1);
}
cout<<Count;
}
//分堆问题
#include <iostream>
#include<string>
#include <math.h>
using namespace std;
int main(int argc, const char * argv[]) {
int n,k;
cin>>n>>k;
int Count=0;
for (int i=0; ; i++) {
if (i%2==1) {
if (n>k) {
Count++;
n-=(k+1);
}else
break;
}else{
if (n>=k) {
Count++;
n-=k;
}else
break;
}
}
cout<<Count;
return 0;
}