#include <bits/stdc++.h>
#include "dna.h"
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 3e3 + 2;
int pa[N][3], pb[N][3], pc[N][3][3];
void init(string s, string t) {
int n = s.size();
vector<int> a(n), b(n);
for (int i = 0; i < n; i++) {
if (s[i] == 'A') a[i] = 0;
if (s[i] == 'C') a[i] = 1;
if (s[i] == 'T') a[i] = 2;
if (t[i] == 'A') b[i] = 0;
if (t[i] == 'C') b[i] = 1;
if (t[i] == 'T') b[i] = 2;
}
for (int i = 0; i < n; i++) {
pa[i][a[i]]++;
pb[i][b[i]]++;
pc[i][a[i]][b[i]]++;
if (i > 0) {
for (int j = 0; j < 3; j++) {
pa[i][j] += pa[i - 1][j];
pb[i][j] += pb[i - 1][j];
for (int jj = 0; jj < 3; jj++) {
pc[i][j][jj] += pc[i - 1][j][jj];
}
}
}
}
}
int Geta(int l, int r, int i) {
int ans = pa[r][i];
if (l > 0) ans -= pa[l - 1][i];
return ans;
}
int Getb(int l, int r, int i) {
int ans = pb[r][i];
if (l > 0) ans -= pb[l - 1][i];
return ans;
}
int Get(int l, int r, int i, int j) {
int ans = pc[r][i][j];
if (l > 0) ans -= pc[l - 1][i][j];
return ans;
}
int get_distance(int l, int r) {
for (int i = 0; i < 3; i++) if (Geta(l, r, i) != Getb(l, r, i)) return -1;
int ans = 0;
int rest = 0;
for (int i = 0; i < 3; i++) {
for (int j = i + 1; j < 3; j++) {
int x = min(Get(l, r, i, j), Get(l, r, j, i));
ans += x;
rest = max(Get(l, r, i, j), Get(l, r, j, i)) - x;
}
}
return ans + 2 * rest;
}
