#include "dna.h"
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define pb push_back
#define mk make_pair
#define fr first
#define sc second
int n;
vector<int> pref[6];
void init(string a, string b) {
n = sz(a);
for(int i = 0; i < 6; i++) pref[i].resize(n+1);
for(int i = 0; i < n; i++) {
for(int j = 0; i > 0 and j < 6; j++) pref[j][i+1] = pref[j][i];
if(a[i] == 'C' and b[i] == 'A') pref[0][i+1]++;
if(a[i] == 'C' and b[i] == 'T') pref[1][i+1]++;
if(a[i] == 'A' and b[i] == 'T') pref[2][i+1]++;
if(a[i] == 'T' and b[i] == 'A') pref[3][i+1]++;
if(a[i] == 'T' and b[i] == 'C') pref[4][i+1]++;
if(a[i] == 'A' and b[i] == 'C') pref[5][i+1]++;
}
}
int get_distance(int x, int y) {
int ans = 0;
int v[6];
for(int i = 0; i < 6; i++)
v[i] = pref[i][y+1] - pref[i][x];
for(int i = 0; i < 3; i++) {
ans += min(v[i], v[5-i]);
v[i] = abs(v[i] - v[5-i]);
}
if(v[0] != v[1] or v[0] != v[2]) return -1;
return ans + 2*v[0];
}
