#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<long long, long long>
string a, b;
map<string, vector<int>> pref;
map<char, vector<int>> apref, bpref;
void init(string a_, string b_) {
a = a_, b = b_;
int n = a.size();
string possible = "ACT";
for (char c1 : possible) {
for (char c2 : possible) {
string t = ""; t += c1; t += c2;
pref[t].resize(n + 1);
}
apref[c1].resize(n + 1);
bpref[c1].resize(n + 1);
}
for (int i = 0; i < n; i++) {
for (auto [str, vec] : pref) {
string t = ""; t += a[i]; t += b[i];
pref[str][i + 1] = pref[str][i] + (t == str);
}
for (auto [chr, vec] : apref) {
apref[chr][i + 1] = apref[chr][i] + (a[i] == chr);
}
for (auto [chr, vec] : bpref) {
bpref[chr][i + 1] = bpref[chr][i] + (b[i] == chr);
}
}
/*for (auto [str, vec] : apref) {
cout << str << ": ";
for (int x : vec) cout << x << " ";
cout << "\n";
}*/
}
int get_distance(signed l, signed r) {
map<string, int> cnt;
map<char, int> acnt, bcnt;
for (auto [str, vec] : pref) {
cnt[str] = vec[r + 1] - vec[l];
}
for (auto [chr, vec] : apref) {
acnt[chr] = vec[r + 1] - vec[l];
}
for (auto [chr, vec] : bpref) {
bcnt[chr] = vec[r + 1] - vec[l];
}
for (auto [chr, _] : acnt) {
//cout << chr << ": " << acnt[chr] << " " << bcnt[chr] << "\n";
if (acnt[chr] != bcnt[chr])
return -1;
}
int atflip = min(cnt["TA"], cnt["AT"]);
int acflip = min(cnt["CA"], cnt["AC"]);
int ctflip = min(cnt["TC"], cnt["CT"]);
int ans = atflip + acflip + ctflip;
cnt["TA"] -= atflip;
cnt["AT"] -= atflip;
cnt["TC"] -= ctflip;
cnt["CT"] -= ctflip;
cnt["CA"] -= acflip;
cnt["AC"] -= acflip;
ans += (cnt["TA"] + cnt["AT"] + cnt["TC"] + cnt["CT"] + cnt["CA"] + cnt["AC"]) / 3 * 2;
return ans;
}
#ifdef ONLINE_JUDGE
signed main() {
init("ATACAT", "ACTATA");
cout << get_distance(1, 3) << "\n";
cout << get_distance(4, 5) << "\n";
cout << get_distance(3, 5) << "\n";
}
#endif
