#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int N = 100000;
int diff[N];
int Aa[N];
int Ca[N];
int Ab[N];
int Cb[N];
void init(std::string a, std::string b)
{
int n = a.length();
for(int i = 0; i < n; i++)
{
diff[i] = 0;
Aa[i] = 0;
Ca[i] = 0;
Ab[i] = 0;
Cb[i] = 0;
}
diff[0] = (a[0] != b[0]);
Aa[0] = (a[0] == 'A');
Ca[0] = (a[0] == 'C');
Ab[0] = (b[0] == 'A');
Cb[0] = (b[0] == 'C');
for(int i = 1; i < n; i++)
{
Aa[i] = Aa[i-1]+(a[i] == 'A');
Ca[i] = Ca[i-1]+(a[i] == 'C');
Ab[i] = Ab[i-1]+(b[i] == 'A');
Cb[i] = Cb[i-1]+(b[i] == 'C');
diff[i] = diff[i-1]+(a[i] != b[i]);
}
}
int get_distance(int x, int y)
{
if(Aa[y] - (x == 0 ? 0 : Aa[x-1]) != Ab[y] - (x== 0 ? 0 : Ab[x-1]) ||
Ca[y] - (x == 0 ? 0 : Ca[x-1]) != Cb[y] - (x== 0 ? 0 : Cb[x-1]))
{
return -1;
}
return max(diff[y] - (x == 0 ? 0 : diff[x-1]) - 1, 0);
}
