#include<bits/stdc++.h>
#include "dna.h"
using namespace std;
const int N=1e5+7;
string a, b, a1, b1;
int n;
int dp[N][30], dp1[N][30];
int dp2[N];
int v[10][N];
vector <string> v1;
map <string,int> mp;
void init(string a0, string b0) {
a = a0;
b = b0;
a1 = a;
b1 = b;
n = a.length();
for (int i=0;i<=n;i++) {
for (int j=0;j<=26;j++) dp[i][j]=dp1[i][j]=0;
}
mp["AC"]=1; mp["AT"]=2;
mp["CA"]=3; mp["CT"]=4;
mp["TA"]=5; mp["TC"]=6;
v1.push_back("AC"); v1.push_back("AT");
v1.push_back("CA"); v1.push_back("CT");
v1.push_back("TA"); v1.push_back("TC");
for (int i=0;i<n;i++){
string s="";
s=s+a[i];
s=s+b[i];
for (int j=0;j<6;j++){
if (v1[j] == s) v[mp[v1[j]]][i+1]=v[mp[v1[j]]][i]+1;
else v[mp[v1[j]]][i+1]=v[mp[v1[j]]][i];
}
}
for (int i=0;i<n;i++){
if (a[i] != b[i]) dp2[i+1]=dp2[i]+1;
else dp2[i+1]=dp2[i];
}
for (int i=0;i<n;i++){
for (char c='A';c<='Z';c++){
if (a[i] == c) dp[i+1][c-'A']=dp[i][c-'A']+1;
else dp[i+1][c-'A']=dp[i][c-'A'];
if (b[i] == c) dp1[i+1][c-'A']=dp1[i][c-'A']+1;
else dp1[i+1][c-'A']=dp1[i][c-'A'];
}
}
}
int get_distance(int x, int y) {
a = a1;
b = b1;
for (int i = 0; i < 26; i++){
if (dp[y+1][i]-dp[x][i] != dp1[y+1][i]-dp1[x][i]) return -1;
}
int arr[10];
for (int i=0;i<6;i++){
int q=v[mp[v1[i]]][y+1]-v[mp[v1[i]]][x];
arr[i+1]=q;
}
int mn=min(arr[1], arr[3]);
int mn1=min(arr[2], arr[5]);
int mn2=min(arr[4], arr[6]);
int q=dp2[y+1]-dp2[x];
int ans=0;
ans=mn+mn1+mn2;
q-=2*(mn+mn1+mn2);
ans+=(q*2)/3;
return ans;
}
