#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int INF = 1e9;
const int MOD = 1e9 + 7;
int n, p1[100002], p2[100002];
void init (string a, string b) {
n = a.size();
map<char, int>mp;
mp['A'] = 1;
mp['C'] = 2;
mp['T'] = 3;
for (int i = 1; i <= n; i++) {
p1[i] = mp[a[i - 1]];
p2[i] = mp[b[i - 1]];
}
}
int get_distance (int x, int y) {
x++;y++;
int cnt[4][4], lol[4];
memset(cnt, 0, sizeof(cnt));
memset(lol, 0, sizeof(lol));
for (int i = x; i <= y; i++) {
lol[p1[i]]--;
lol[p2[i]]++;
cnt[p1[i]][p2[i]]++;
}
if (lol[1] != 0 || lol[2] != 0 || lol[3] != 0)
return -1;
int cycles = 0;
int sz = y - x + 1;
cycles += cnt[1][1];
cycles += cnt[2][2];
cycles += cnt[3][3];
sz -= cycles;
cycles += min(cnt[1][2], cnt[2][1]);
sz -= 2 * min(cnt[1][2], cnt[2][1]);
cycles += min(cnt[1][3], cnt[3][1]);
sz -= 2 * min(cnt[1][3], cnt[3][1]);
cycles += min(cnt[2][3], cnt[3][2]);
sz -= 2 * min(cnt[2][3], cnt[3][2]);
cycles += sz / 3;
return y - x + 1 - cycles;
}
