#include <bits/stdc++.h>
using namespace std;
vector<int> cntAA, cntTA, cntCA;
vector<int> cntAB, cntTB, cntCB;
vector<int> diffs;
int n;
void init(string a, string b) {
n = a.size();
cntAA.assign(n, 0), cntTA.assign(n, 0), cntCA.assign(n, 0);
cntAB.assign(n, 0), cntTB.assign(n, 0), cntCB.assign(n, 0);
for (int i = 0; i < n; i++) {
if (a[i] == 'A') cntAA[i]++;
else if (a[i] == 'T') cntTA[i]++;
else cntCA[i]++;
if (b[i] == 'A') cntAB[i]++;
else if (b[i] == 'C') cntCB[i]++;
else cntTB[i]++;
}
diffs.assign(n, 0);
for (int i = 0; i < n; i++) {
if (a[i] != b[i]) diffs[i]++;
}
for (int i = 1; i < n; i++) {
diffs[i] += diffs[i-1];
cntAA[i] += cntAA[i-1];
cntCA[i] += cntCA[i-1];
cntTA[i] += cntTA[i-1];
cntAB[i] += cntAB[i-1];
cntCB[i] += cntCB[i-1];
cntTB[i] += cntTB[i-1];
}
}
int get_distance(int x, int y) {
if (x == 0) {
if (cntAA[y] != cntAB[y]
|| cntCA[y] != cntCB[y]
|| cntTA[y] != cntTB[y]) return -1;
}
else {
if (cntAA[y] - cntAA[x-1] != cntAB[y] - cntAB[x-1]
|| cntCA[y] - cntCA[x-1] != cntCB[y] - cntCB[x-1]
|| cntTA[y] - cntTA[x-1] != cntTB[y] - cntTB[x-1]) return -1;
}
if (x == 0) {
return diffs[y] / 2 + (diffs[y] % 2);
}
else {
int k = diffs[y] - diffs[x-1];
return k / 2 + (k % 2);
}
}
/*
int main() {
init("ATACAT", "ACTATA");
cout << get_distance(1, 3) << "\n" << get_distance(4, 5) << "\n" << get_distance(3, 5) << "\n";
return 0;
}*/
