#include <iostream>
#include <cmath>
using namespace std;
int n;
int cnt[100002][3];
int sum[100002][3][3];
void init(string a, string b) {
n = (int)a.size();
for (int i = 1; i <= n; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 3; k++) {
sum[i][j][k] = sum[i - 1][j][k];
}
}
for (int j = 0; j < 3; j++) {
cnt[i][j] = cnt[i - 1][j];
}
sum[i][a[i - 1] == 'A' ? 0 : a[i - 1] == 'T' ? 1 : 2][b[i - 1] == 'A' ? 0 : b[i - 1] == 'T' ? 1 : 2]++;
cnt[i][a[i - 1] == 'A' ? 0 : a[i - 1] == 'T' ? 1 : 2]++;
cnt[i][b[i - 1] == 'A' ? 0 : b[i - 1] == 'T' ? 1 : 2]--;
}
}
int get_distance(int x, int y) {
x++, y++;
int ans = 0;
int c[3][3] = { {0} };
for (int i = 0; i < 3; i++) for (int j = 0; j < 3; j++) {
c[i][j] = sum[y][i][j] - sum[x - 1][i][j];
}
if (cnt[y][0] != cnt[x - 1][0]) {
return -1;
}
if (cnt[y][1] != cnt[x - 1][1]) {
return -1;
}
if (cnt[y][2] != cnt[x - 1][2]) {
return -1;
}
int tmp;
tmp = min(c[0][1], c[1][0]);
c[0][1] -= tmp, c[1][0] -= tmp, ans += tmp;
tmp = min(c[0][2], c[2][0]);
c[0][2] -= tmp, c[2][0] -= tmp, ans += tmp;
tmp = min(c[2][1], c[1][2]);
c[2][1] -= tmp, c[1][2] -= tmp, ans += tmp;
ans += 2 * (c[0][1] + c[1][0]);
return ans;
}
