#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ld long double
#define vf v[i].first
#define vs v[i].second
const ll MOD = 1e9 + 7;
void print(vector<ll> &v) {
for (auto c:v)
cout << c << " ";
cout << "\n";
}
int n;
string c,d;
void init(string a, string b) {
n = a.size();
c = a;
d = b;
}
int get_distance(int x, int y) {
int ans = 0;
string t1 = c.substr(x,y-x+1), t2 = d.substr(x,y-x+1);
sort(t1.begin(),t1.end());
sort(t2.begin(),t2.end());
if (t1!=t2)
return -1;
t1 = c.substr(x,y-x+1), t2 = d.substr(x,y-x+1);
for (int i = 0; i < y-x+1; ++i) {
if (t1[i]!=t2[i])
++ans;
}
return ans/2;
}
/*int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
string a,b;
cin >> a >> b;
init(a,b);
cout << get_distance(0,2);
}
*/
