#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int C = 3;
const int MXN = 1e5 + 10;
int n;
int qs[MXN][3][3];
inline int parse(char c) {
if (c == 'A') return 0;
if (c == 'C') return 1;
return 2;
}
void init(std::string a, std::string b) {
n = a.size();
for (int i = 1; i <= n; i++) {
for (int j = 0; j < C; j++) {
for (int k = 0; k < C; k++) {
qs[i][j][k] += qs[i - 1][j][k];
}
}
int x = parse(a[i - 1]);
int y = parse(b[i - 1]);
qs[i][x][y] += 1;
}
}
int get_distance(int x, int y) {
x += 1, y += 1;
int sum[3][3] = {};
int used[3] = {};
for (int j = 0; j < C; j++) {
for (int k = 0; k < C; k++) {
sum[j][k] = qs[y][j][k] - qs[x - 1][j][k];
}
}
used[0] = min(sum[0][1], sum[1][0]);
used[1] = min(sum[0][2], sum[2][0]);
used[2] = min(sum[1][2], sum[2][1]);
sum[0][1] -= used[0], sum[1][0] -= used[0];
sum[0][2] -= used[1], sum[2][0] -= used[1];
sum[2][1] -= used[2], sum[1][2] -= used[2];
if (sum[0][1] != sum[1][2] or sum[1][2] != sum[2][0] or sum[1][0] != sum[0][2] or sum[0][2] != sum[2][1]) return -1;
return max(sum[0][1], sum[1][0]) * 2 + used[0] + used[1] + used[2];
}
