#include <bits/stdc++.h>
using namespace std;
int const N=1e5+5;
int n;
string a,b;
// int preA[N],preT[N],preC[N];
int AT[N],TC[N],CA[N];
int eq[N];
void init(string aa,string bb){
n=aa.length();
a=aa;
b=bb;
for (int i = 1; i <=n; ++i)
{
// preA[i]=preA[i-1];
// preT[i]=preT[i-1];
// preC[i]=preC[i-1];
AT[i]=AT[i-1];
CA[i]=CA[i-1];
TC[i]=TC[i-1];
eq[i]=eq[i-1];
// if(b[i-1]=='A')
// preA[i]++;
// else if(b[i-1]=='T')
// preT[i]++;
// else
// preC[i]++;
if(a[i-1]==b[i-1])
eq[i]++;
else if(a[i-1]=='A'&&b[i-1]=='T')
AT[i]++;
else if(a[i-1]=='T'&&b[i-1]=='A')
AT[i]--;
else if(a[i-1]=='T'&&b[i-1]=='C')
TC[i]++;
else if(a[i-1]=='C'&&b[i-1]=='T')
TC[i]--;
else if(a[i-1]=='C'&&b[i-1]=='A')
CA[i]++;
else
CA[i]--;
}
}
int get_distance(int x, int y){
//check
y++;
int one=AT[y]-AT[x];
int two=TC[y]-TC[x];
int three=CA[y]-CA[x];
// cout<<one<<' '<<two<<' '<<three<<endl;
if(one!=two || one!=three)
return -1;
int ans=abs(one)*2;
int tot=y-x;
tot-=(eq[y]-eq[x]);
tot-=abs(one)*3;
ans+=tot/2;
return ans;
}
