#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
constexpr int NMAX = 1e5 + 5;
int N;
int pref[NMAX][3][3];
int fr[NMAX][3];
int Value (char ch) {
if (ch == 'A') return 0;
if (ch == 'C') return 1;
return 2;
}
void init(std::string a, std::string b) {
N = a.size();
for (int i = 1; i <= N; ++ i ) {
pref[i][Value(a[i-1])][Value(b[i-1])] = 1;
for (int j = 0; j < 3; ++ j )
for (int k = 0; k < 3; ++ k )
pref[i][j][k] += pref[i-1][j][k];
fr[i][Value(a[i-1])] ++;
fr[i][Value(b[i-1])] --;
for (int j = 0; j < 3; ++ j )
fr[i][j] += fr[i-1][j];
}
}
int get_distance(int x, int y) {
int mat[3][3];
memset(mat, 0, sizeof(mat));
int freq[3];
memset(freq, 0, sizeof(freq));
for (int i = 0; i < 3; ++ i )
for (int j = 0; j < 3; ++ j )
mat[i][j] = pref[y+1][i][j] - pref[x][i][j];
for (int i = 0; i < 3; ++ i )
freq[i] = fr[y+1][i] - fr[x][i];
bool ok = 1;
for (int i = 0; i < 3; ++ i )
if (freq[i] != 0) ok = 0;
if (!ok) return -1;
int ans = 0;
for (int i = 0; i < 3; ++ i ) {
for (int j = i+1; j < 3; ++ j ) {
int value = min(mat[i][j], mat[j][i]);
ans = ans + value;
mat[i][j] -= value;
mat[j][i] -= value;
}
}
int Max = 0;
for (int i = 0; i < 3; ++ i ) {
for (int j = 0; j < 3; ++ j ) {
if (i == j) continue;
Max = max(Max, mat[i][j]);
}
}
return ans + 2 * Max;
}
