#include <bits/stdc++.h>
#include "dna.h"
using namespace std;
string A,B;
vector<int> a_T,a_A,b_T,b_A,diff;
void init(std::string a, std::string b) {
A = a;
B = b;
a_A.resize(A.size()+1);
b_A.resize(A.size()+1);
b_T.resize(A.size()+1);
a_T.resize(A.size()+1);
diff.resize(A.size()+1);
for(int i=0;i<A.size();++i)
{
a_A[i+1]+=a_A[i];
a_T[i+1]+=a_T[i];
b_A[i+1]+=b_A[i];
b_T[i+1]+=b_T[i];
if(A[i] == 'A')
++a_A[i+1];
else
++a_T[i+1];
if(B[i] == 'A')
++b_A[i+1];
else
++b_T[i+1];
if(A[i] != B[i])
{
++diff[i+1];
}
}
}
int get_distance(int x, int y) {
int at = a_T[y+1] - a_T[x];
int aa = a_A[y+1] - a_A[x];
int bt = b_T[y+1] - b_T[x];
int ba = b_A[y+1] - b_A[x];
int difff = diff[y+1] - diff[x];
if(difff & 1)
return -1;
if(at != bt || aa != ba)
return -1;
return difff / 2;
}
