#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
string A, B;
int N;
vector<vector<int>> ps;
void init(std::string a, std::string b)
{
int N = a.size();
// Construct prefix sums
ps = vector<vector<int>>(N+1, vector<int>(6));
for (int i = 0; i < N; i++)
{
for (int j = 0; j < 6; j++)
ps[i+1][j] = ps[i][j];
if (a[i] == 'A' && b[i] == 'T')
ps[i+1][0]++;
if (a[i] == 'A' && b[i] == 'C')
ps[i+1][1]++;
if (a[i] == 'C' && b[i] == 'T')
ps[i+1][2]++;
if (a[i] == 'T' && b[i] == 'A')
ps[i+1][3]++;
if (a[i] == 'C' && b[i] == 'A')
ps[i+1][4]++;
if (a[i] == 'T' && b[i] == 'C')
ps[i+1][5]++;
}
}
int get_distance(int x, int y)
{
vector<int> v(6);
for (int i = 0; i < 6; i++)
v[i] = ps[y+1][i] - ps[x][i];
int res = 0;
for (int i = 0; i < 3; i++)
{
int n = min(v[i], v[i+3]);
res += n;
v[i] -= n;
v[i+3] -= n;
}
if (v[0] + v[3] != v[1] + v[4] || v[0] + v[3] != v[2] + v[5])
return -1;
return res + (v[0] + v[3]) * 2;
}
