#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
int n;
array<array<vector<int>, 3>, 3> v;
void init(std::string a, std::string b) {
n = a.size();
for (int i = 0; i < n; ++i) {
if (a[i] == 'T') a[i] = 'B';
if (b[i] == 'T') b[i] = 'B';
}
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 3; ++j) {
v[i][j].assign(n + 1, 0);
}
}
for (int i = 0; i < n; ++i) {
for (int a = 0; a < 3; ++a) {
for (int b = 0; b < 3; ++b) {
v[a][b][i + 1] = v[a][b][i];
}
}
v[a[i] - 'A'][b[i] - 'A'][i + 1]++;
}
}
int get_distance(int x, int y) {
int ans = 0;
array<array<int, 3>, 3> c;
array<int, 3> tot = {0, 0, 0};
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 3; ++j) {
if (i == j) continue;
c[i][j] = v[i][j][y + 1] - v[i][j][x];
tot[i] += c[i][j];
tot[j] -= c[i][j];
}
}
if (count(tot.begin(), tot.end(), 0) != 3) return -1;
int left = 0;
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < i; ++j) {
int cur = min(c[i][j], c[j][i]);
c[i][j] -= cur;
c[j][i] -= cur;
left = c[i][j] + c[j][i];
ans += cur;
}
}
ans += left * 2;
return ans;
}
