#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
int is(char c) {
if (c=='A') return 0;
else if (c=='C') return 1;
return 2;
}
vector<vector<int>> prefa, prefb;
vector<int> diff;
void init(string a, string b) {
prefa.push_back({0, 0, 0}), prefb.push_back({0, 0, 0}), diff.push_back(0);
for (int i=0; i<(int)a.size(); i++) {
prefa.push_back(prefa.back()), prefb.push_back(prefb.back()), diff.push_back(diff.back());
prefa.back()[is(a[i])]++, prefb.back()[is(b[i])]++, diff.back()+=a[i]!=b[i];
}
}
int get_distance(int x, int y) {
if (prefa[y+1][0]-prefa[x][0]!=prefb[y+1][0]-prefb[x][0] || prefa[y+1][1]-prefa[x][1]!=prefb[y+1][1]-prefb[x][1] || prefa[y+1][2]-prefa[x][2]!=prefb[y+1][2]-prefb[x][2]) return -1;
return (diff[y+1]-diff[x]+1)/2;
}
