#include <bits/stdc++.h>
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
using namespace std;
const int N = 1e5 + 5;
int pref[3][3][N];
int s1[3][N];
int s2[3][N];
map<char, int> f;
void init(string a, string b) {
f['A'] = 0;
f['C'] = 1;
f['T'] = 2;
int n = (int) a.size();
a = ' ' + a;
b = ' ' + b;
for (int i = 1; i <= n; i++) {
for (int k = 0; k < 3; k++) {
for (int l = 0; l < 3; l++) {
pref[k][l][i] = pref[k][l][i - 1] + (f[a[i]] == k && f[b[i]] == l);
}
s1[k][i] = s1[k][i - 1] + (f[a[i]] == k);
s2[k][i] = s2[k][i - 1] + (f[b[i]] == k);
}
}
}
int get_distance(int x, int y) {
x++;
y++;
for (int t = 0; t < 3; t++) {
if (s1[t][y] - s1[t][x - 1] != s2[t][y] - s2[t][x - 1]) {
return -1;
}
}
int ans = 0, kk = 0;
for (int k = 0; k < 3; k++) {
for (int l = k + 1; l < 3; l++) {
ans += min(pref[k][l][y] - pref[k][l][x - 1], pref[l][k][y] - pref[l][k][x - 1]);
if (k == 0 and l == 1) kk = abs((pref[k][l][y] - pref[k][l][x - 1]) - (pref[l][k][y] - pref[l][k][x - 1]));
}
}
return ans + 2 * kk;
}
//int main() {
// ios_base::sync_with_stdio(false);
// cin.tie(0), cout.tie(0);
//
//// file("A") else file("task");
//
// return 0;
//}
