#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ss second
#define ff first
#define pb push_back
#define mk make_pair
#define mt make_tuple
string X,s;
void init(string a,string b){
X=a;s=b;
}
int get_distance(int x,int y){
int l=x,r=y;
map<char,int>mp,ms;
for(int i=l;i<=r;i++){
mp[X[i]]++;
ms[s[i]]++;
}
for(int i=0;i<26;i++){
if(mp[i]!=ms[i]){
return -1;
}
}
vector<int>aC,aT,tC,cT,tA,cA;
for(int i=l;i<=r;i++){
if(s[i]=='A'&&X[i]=='C'){
aC.pb(i);
}
if(s[i]=='A'&&X[i]=='T'){
aT.pb(i);
}
if(s[i]=='T'&&X[i]=='C'){
tC.pb(i);
}
if(s[i]=='T'&&X[i]=='A'){
tA.pb(i);
}
if(s[i]=='C'&&X[i]=='T'){
cT.pb(i);
}
if(s[i]=='C'&&X[i]=='A'){
cA.pb(i);
}
}
reverse(aC.begin(),aC.end());
reverse(cA.begin(),cA.end());
reverse(aT.begin(),aT.end());
reverse(tA.begin(),tA.end());
reverse(cT.begin(),cT.end());
reverse(tC.begin(),tC.end());
int ans=0;
for(int i=l;i<=r;i++){
if(s[i]=='A'&&X[i]=='C'&&cA.size()>0){
swap(X[cA.size()-1],X[i]);
ans++;
cA.pop_back();
aC.pop_back();
// cout<<"#1\n";
}
if(s[i]=='A'&&X[i]=='T'&&tA.size()>0){
swap(X[tA.size()-1],X[i]);
ans++;
tA.pop_back();
aT.pop_back();
// cout<<"#2\n";
}
if(s[i]=='T'&&X[i]=='C'&&cT.size()>0){
swap(X[cT[cT.size()-1]],X[i]);
ans++;
cT.pop_back();
tC.pop_back();
//cout<<"#3\n"<<X<<" "<<s<<endl;
}
if(s[i]=='T'&&X[i]=='A'&&aT.size()>0){
swap(X[aT.size()-1],X[i]);
ans++;
aT.pop_back();
tA.pop_back();
// cout<<"#4\n";
}
if(s[i]=='C'&&X[i]=='T'&&tC.size()>0){
swap(X[tC[tC.size()-1]],X[i]);
ans++;
tC.pop_back();
cT.pop_back();
// cout<<"#5\n"<<X<<" "<<s<<endl;
}
if(s[i]=='C'&&X[i]=='A'&&aC.size()>0){
swap(X[aC.size()-1],X[i]);
ans++;
aC.pop_back();
cA.pop_back();
// cout<<"#6\n";
}
}
int o=0;
for(int i=l;i<=r;i++){
if(X[i]!=s[i]){
o++;
}
}
//cout<<X<<" "<<s;
ans+=o/3*2;
return ans;
}
