#include <bits/stdc++.h>
using namespace std;
//CTA
const int N = 1e5+7;
int TC[N], AC[N], AT[N];
int CT[N], CA[N], TA[N];
void init(string A, string B){
int n = A.size();
for (int i=0; i<n; i++){
TC[i+1] = TC[i] + (A[i] == 'T' && B[i] == 'C');
AC[i+1] = AC[i] + (A[i] == 'A' && B[i] == 'C');
AT[i+1] = AT[i] + (A[i] == 'A' && B[i] == 'T') ;
CT[i+1] = CT[i] + (A[i] == 'C' && B[i] == 'T') ;
CA[i+1] = CA[i] + (A[i] == 'C' && B[i] == 'A');
TA[i+1] = TA[i] + (A[i] == 'T' && B[i] == 'A');
}
}
int get_distance(int x, int y){
int tc = TC[y+1] - TC[x];
int ac = AC[y+1] - AC[x];
int at = AT[y+1] - AT[x];
int ct = CT[y+1] - CT[x];
int ca = CA[y+1] - CA[x];
int ta = TA[y+1] - TA[x];
// cout<<tc<<' '<<ac<<' '<<at<<' '<<ct<<' '<<ca<<' '<<ta<<'\n';
int r1 = min(tc,ct); tc-=r1, ct-=r1;
int r2 = min(ac,ca); ca-=r2, ac-=r2;
int r3 = min(at,ta); at-=r3, ta-=r3;
int res = r1+r2+r3;
if ((tc+ta != at+ct) || (ac+at != ta+ca) || (tc+ac != ca+ct)) return -1;
res += 2*(tc+ac+at+ct+ca+ta)/3;
return res;
}
// int main(){
// init("ATACAT", "ACTATA");
// cout<<get_distance(1,3)<<'\n';
// cout<<get_distance(4,5)<<'\n';
// cout<<get_distance(3,5)<<'\n';
// }
