#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int mxN = 1e5 + 1;
int ps[mxN][3][3];
int check[2][mxN][3];
unordered_map<char, int> conv = {{'A', 0}, {'C', 1}, {'T', 2}};
int n;
void init(string a, string b) {
n = a.length();
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
ps[0][i][j] = 0;
}
check[0][0][i] = check[1][0][i] = 0;
}
for (int i = 1; i <= n; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 3; k++) {
ps[i][j][k] = ps[i - 1][j][k];
}
check[0][i][j] = check[0][i - 1][j];
check[1][i][j] = check[1][i - 1][j];
}
ps[i][conv[a[i - 1]]][conv[b[i - 1]]]++;
check[0][i][conv[a[i - 1]]]++;
check[1][i][conv[b[i - 1]]]++;
}
}
int get_distance(int x, int y) {
x++; y++;
for (int i = 0; i < 3; i++) {
if (check[0][y][i] - check[0][x - 1][i] != check[1][y][i] - check[1][x - 1][i]) {
return -1;
}
}
int diff[6];
diff[0] = ps[y][0][1] - ps[x - 1][0][1];
diff[1] = ps[y][0][2] - ps[x - 1][0][2];
diff[2] = ps[y][1][0] - ps[x - 1][1][0];
diff[3] = ps[y][1][2] - ps[x - 1][1][2];
diff[4] = ps[y][2][0] - ps[x - 1][2][0];
diff[5] = ps[y][2][1] - ps[x - 1][2][1];
int ans = 0;
int cur;
// 01
cur = min(diff[0], diff[2]);
diff[0] -= cur; diff[2] -= cur;
ans += cur;
// 02
cur = min(diff[1], diff[4]);
diff[1] -= cur; diff[4] -= cur;
ans += cur;
// 12
cur = min(diff[3], diff[5]);
diff[3] -= cur; diff[5] -= cur;
ans += cur;
// 012
cur = min({diff[0], diff[3], diff[4]});
diff[0] -= cur; diff[3] -= cur; diff[4] -= cur;
ans += cur * 2;
// 210
cur = min({diff[5], diff[2], diff[1]});
diff[5] -= cur; diff[2] -= cur; diff[1] -= cur;
ans += cur * 2;
return ans;
}
