#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int MXN = 100000;
int cnt[MXN][3][3];
int cur[3][3];
void init(string a, string b) {
map<char, int> mp;
mp['A'] = 0, mp['T'] = 1, mp['C'] = 2;
int N = a.size();
for(int i = 0; i < N; i++){
if(i) for(int j = 0; j < 3; j++)
for(int k = 0; k < 3; k++)
cnt[i][j][k] = cnt[i-1][j][k];
cnt[i][mp[a[i]]][mp[b[i]]]++;
}
}
int get_distance(int l, int r) {
auto get_inv = [&](int x, int y){
return cnt[r][x][y] - (l ? cnt[l-1][x][y] : 0);
};
for(int i = 0; i < 3; i++)
for(int j = 0; j < 3; j++)
cur[i][j] = get_inv(i, j);
int ans = 0;
for(int i = 0; i < 3; i++){
int j = (i + 1) % 3;
int x = min(cur[i][j], cur[j][i]);
cur[j][i] -= x, cur[i][j] -= x;
ans += x;
}
bool pos = 1;
for(int i = 0; i < 3; i++) pos &= (cur[i][(i + 1)%3] == cur[0][1]);
for(int i = 0; i < 3; i++) pos &= (cur[(i + 1)%3][i] == cur[1][0]);
if(!pos) return -1;
return ans + 2*(cur[0][1] + cur[1][0]);
}
