#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
string s, t;
int ps[N][3][3], n;
int f (char c) {
return c % 3;
}
void init(std::string a, std::string b) {
s = a;
t = b;
n = (int)s.size();
for (int i = 0; i < n; i++) {
ps[i][f(s[i])][f(t[i])]++;
if (i) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 3; k++) {
ps[i][j][k] += ps[i - 1][j][k];
}
}
}
}
}
int get_distance(int x, int y) {
int a[3][3], b[3] = {};
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
a[i][j] = ps[y][i][j] - (x ? ps[x - 1][i][j] : 0);
b[i] += a[i][j];
b[j] -= a[i][j];
}
}
int ans = 0;
bool f = true;
for (int i = 0; i < 3; i++ ){
if (b[i] != 0)
f = false;
for (int j = i + 1; j < 3; j++){
int k = min(a[i][j], a[j][i]);
ans += k;
a[i][j] -= k;
a[j][i] -= k;
}
}
int mn = INT_MAX, cnt = 0;
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
if (i != j) {
ans += a[i][j];
if (a[i][j]) {
mn = min (mn, a[i][j]);
cnt++;
}
}
}
}
if (cnt == 3) {
ans -= mn;
}
return (f ? ans : -1);
}
