#include <bits/stdc++.h>
#include "dna.h"
using namespace std;
string A, B;
void init(string a, string b){
A = a, B = b;
}
int get_distance(int x, int y){
assert((y - x) <= 2);
if(x == y){
if(A[x] == B[x]) return 0;
else return -1;
}else if(y == x + 1){
if(A[x] == B[x] && A[y] == B[y]) return 0;
else if(A[x] == B[y] && A[y] == B[x]) return 1;
else return -1;
}else{
bool ok = 1;
int cnt = 0;
map<char,int> mp1, mp2;
for(int i = x; i <= y; ++i){
ok &= A[i] == B[i];
++mp1[A[i]], ++mp2[B[i]];
cnt += A[i] == B[i];
}
if(ok) return 0;
else if(mp1 == mp2){
if(cnt == 0) return 2;
return 1;
}else return -1;
}
}
/*int main(){
#ifndef ONLINE_JUDGE
freopen("inp.in", "r", stdin);
freopen("output.out", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
return 0;
}*/
