#include "dna.h"
using namespace std;
#define ll long long
#define add push_back
#define len(a) ((int)(a).size())
#define all(a) a.begin(), a.end()
const int N = 1e5 + 5;
int cnt[2][N][5];
int c[N][5][5];
void init(string a, string b) {
for(int i = 0; i < len(a); i++){
cnt[0][i + 1][0] = cnt[0][i][0] + (a[i] == 'A');
cnt[0][i + 1][1] = cnt[0][i][1] + (a[i] == 'C');
cnt[0][i + 1][2] = cnt[0][i][2] + (a[i] == 'T');
c[i + 1][0][1] = c[i][0][1] + (a[i] == 'A' && b[i] == 'C');
c[i + 1][0][2] = c[i][0][2] + (a[i] == 'A' && b[i] == 'T');
c[i + 1][1][0] = c[i][1][0] + (a[i] == 'C' && b[i] == 'A');
c[i + 1][1][2] = c[i][1][2] + (a[i] == 'C' && b[i] == 'T');
c[i + 1][2][0] = c[i][2][0] + (a[i] == 'T' && b[i] == 'A');
c[i + 1][2][1] = c[i][2][1] + (a[i] == 'T' && b[i] == 'C');
}
for(int i = 0; i < len(b); i++){
cnt[1][i + 1][0] = cnt[1][i][0] + (b[i] == 'A');
cnt[1][i + 1][1] = cnt[1][i][1] + (b[i] == 'C');
cnt[1][i + 1][2] = cnt[1][i][2] + (b[i] == 'T');
}
}
int get_distance(int x, int y) {
if(cnt[0][y + 1][0] - cnt[0][x][0] != cnt[1][y + 1][0] - cnt[1][x][0]) return -1;
if(cnt[0][y + 1][1] - cnt[0][x][1] != cnt[1][y + 1][1] - cnt[1][x][1]) return -1;
if(cnt[0][y + 1][2] - cnt[0][x][2] != cnt[1][y + 1][2] - cnt[1][x][2]) return -1;
int sum = 0, ret = 0, now;
sum += c[y + 1][0][1] + c[y + 1][0][2] + c[y + 1][1][0] + c[y + 1][1][2] + c[y + 1][2][0] + c[y + 1][2][1] - (c[x][0][1] + c[x][0][2] + c[x][1][0] + c[x][1][2] + c[x][2][0] + c[x][2][1]);
now = min(c[y + 1][0][1] - c[x][0][1], c[y + 1][1][0] - c[x][1][0]);
ret += now;
sum -= 2 * now;
now = min(c[y + 1][0][2] - c[x][0][2], c[y + 1][2][0] - c[x][2][0]);
ret += now;
sum -= 2 * now;
now = min(c[y + 1][2][1] - c[x][2][1], c[y + 1][1][2] - c[x][1][2]);
ret += now;
sum -= 2 * now;
ret += (sum / 3) * 2;
return ret;
}
