#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int MAXN = 1e5 + 7;
ll pref[MAXN][7][10];
ll same[MAXN];
void init(string a, string b) {
for(ll i = 0; i < a.size(); i++) {
for(ll j = 0; j < 2; j++)
for(ll k = 0; k < 3; k++)
pref[i + 1][j][k] += pref[i][j][k];
pref[i + 1][1][(b[i] == 'A' ? 0 : (b[i] == 'C' ? 1 : 2))]++;
pref[i + 1][0][(a[i] == 'A' ? 0 : (a[i] == 'C' ? 1 : 2))]++;
same[i + 1] = same[i] + !(a[i] == b[i]);
}
}
int get_distance(int x, int y) {
x++, y++;
if(pref[y][1][0] - pref[x - 1][1][0] != pref[y][0][0] - pref[x - 1][0][0]
|| pref[y][1][1] - pref[x - 1][1][1] != pref[y][0][1] - pref[x - 1][0][1]
|| pref[y][1][2] - pref[x - 1][1][2] != pref[y][0][2] - pref[x - 1][0][2])
return -1;
return (same[y] - same[x - 1]) / 2LL + ((same[y] - same[x - 1]) % 2LL);
}
