// #include "dna.h"
#include <bits/stdc++.h>
using namespace std;
int n;
vector<vector<int>> pref(6, vector<int>(111111));
vector<vector<int>> pref2(3, vector<int>(111111));
void init(string a, string b) {
map<string, int> cd;
cd["AT"] = 0;
cd["TC"] = 1;
cd["CA"] = 2;
cd["AC"] = 3;
cd["CT"] = 4;
cd["TA"] = 5;
n = a.size();
a = '?' + a;
b = '?' + b;
for (int i = 1; i <= n; i++) {
for (int j = 0; j < 6; j++) {
pref[j][i] = pref[j][i-1];
}
for (int j = 0; j < 3; j++) {
pref2[j][i] = pref2[j][i-1];
}
pref2[(a[i] == 'A' ? 0 : a[i] == 'T' ? 1 : 2)][i]++;
pref2[(b[i] == 'A' ? 0 : b[i] == 'T' ? 1 : 2)][i]--;
if (a[i] == b[i]) continue;
string x = "";
x.push_back(a[i]);
x.push_back(b[i]);
pref[cd[x]][i]++;
}
}
int get_distance(int x, int y) {
++x;
++y;
vector<int> ct(6);
for (int j = 0; j < 6; j++) {
ct[j] = pref[j][y] - pref[j][x-1];
}
for (int j = 0; j < 3; j++) {
if (pref2[j][y] - pref2[j][x-1] != 0) {
return -1;
}
}
int ans = 0;
for (int j = 0; j < 3; j++) {
int z = min(ct[j], ct[5-j]);
ct[j] -= z;
ct[5-j] -= z;
ans += z;
}
ans += 2*(ct[0] + ct[3]);
return ans;
}
