#include "dna.h"
#include<bits/stdc++.h>
using namespace std;
vector<vector<int>> ps;
void init(string a, string b){
int n = a.size();
ps.resize(n+1, vector<int>(6, 0));
for (int i=0; i<n; i++){
ps[i+1][0] = ps[i][0]+(a[i] == 'A' && b[i] == 'T');
ps[i+1][1] = ps[i][1]+(a[i] == 'T' && b[i] == 'A');
ps[i+1][2] = ps[i][2]+(a[i] == 'A' && b[i] == 'C');
ps[i+1][3] = ps[i][3]+(a[i] == 'C' && b[i] == 'A');
ps[i+1][4] = ps[i][4]+(a[i] == 'T' && b[i] == 'C');
ps[i+1][5] = ps[i][5]+(a[i] == 'C' && b[i] == 'T');
}
}
int get_distance(int x, int y){
vector<int> v(6);
for (int i=0; i<6; i++) v[i] = ps[y+1][i]-ps[x][i];
int a = min(v[0], v[1])+min(v[2], v[3])+min(v[4], v[5]);
if (v[0]+v[2] != v[1]+v[3] || v[1]+v[4] != v[0]+v[5] || v[3]+v[5] != v[2]+v[4]) return -1;
return a+(v[0]+v[1]+v[2]+v[3]+v[4]+v[5]-2*a)/3*2;
}
