#include "dna.h"
#include<bits/stdc++.h>
#define in insert
#define pb push_back
using namespace std;
const int N=1e5+5;
int n,B[N],C[N],pref[N][2];
void init(std::string a, std::string b){
n=a.size();
for(int i=1;i<=n;i++){
if(a[i-1]=='A') B[i]=1;
else if(a[i-1]=='T') B[i]=2;
else B[i]=3;
}
for(int i=1;i<=n;i++){
if(b[i-1]=='A') C[i]=1;
else if(b[i-1]=='T') C[i]=2;
else C[i]=3;
}
for(int i=1;i<=n;i++){
//pref[i]=pref[i-1];
if(B[i]==1 && C[i]==2) pref[i][0]++;
if(B[i]==2 && C[i]==1) pref[i][1]++;
}
return ;
}
int get_distance(int x, int y){
++x;++y;
vector<int> v[2][3];
int ret=0;
for(int i=x;i<=y;i++){
v[0][B[i]].pb(i);
v[1][C[i]].pb(i);
}
if(v[0][1].size()!=v[1][1].size()) return -1;
for(int i=x;i<=y;i++) ret+=bool(C[i]!=B[i]);
return ret/2;
}
