#include "dna.h"
#include <bits/stdc++.h>
#include <string>
#include <iostream>
#include <cmath>
#include <numeric>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<int, int> pl;
typedef pair<ld, ld> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<ld> vd;
typedef vector<long> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define len(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define F first
#define nl endl
#define S second
#define lb lower_bound
#define ub upper_bound
#define aint(x) x.begin(), x.end()
#define raint(x) x.rbegin(), x.rend()
#define ins insert
const int MOD = 1000000007;
vvi A(100010, vi(3,0));
vvi B(100010, vi(3,0));
vvi types(100010, vi(23,0));
int to_int(char a){
if(a == 'A')return 0;
if(a == 'C')return 1;
return 2;
}
int to_pair(char a,char b){
return to_int(a)*10+to_int(b);
}
void init(std::string a, std::string b) {
FOR(i,1,a.size()+1){
FOR(j,0,3)A[i][j] = A[i-1][j];
FOR(j,0,3)B[i][j] = B[i-1][j];
FOR(j,0,23)types[i][j] = types[i-1][j];
A[i][to_int(a[i-1])] += 1;
B[i][to_int(b[i-1])] += 1;
types[i][to_pair(a[i-1],b[i-1])] += 1;
}
// FOR(i,0,a.size()+1){
// FOR(j,0,3){
// cout << A[i][j] << " ";
// }cout << endl;
// }cout << endl;
// FOR(i,0,a.size()+1){
// FOR(j,0,3){
// cout << B[i][j] << " ";
// }cout << endl;
// }cout << endl;
}
int ans = 0;
int num_errors = 0;
void quick(int x,int y,int a,int b){
int temp = min(types[y][a] - types[x][a],types[y][b] - types[x][b]);
num_errors -= temp * 2;
ans += temp;
}
int get_distance(int x, int y) {
// cout << "############" << endl;
y++;
FOR(i,0,3){
// cout << i << " " << A[y][i] << " - " << A[x][i] << " " << B[y][i] << " - " << B[x][i] << endl;
if(A[y][i] - A[x][i] != B[y][i] - B[x][i])return -1;
}
ans = 0;
num_errors = 0;
FOR(j,0,23){
if(j==0)continue;
if(j==11)continue;
if(j==22)continue;
num_errors += types[y][j] - types[x][j];
}
quick(x,y,1,10);
quick(x,y,2,20);
quick(x,y,12,21);
ans += (num_errors/3)*2;
return ans;
}
