#include "dna.h"
#include <map>
#include <iostream>
using namespace std;
int const N=1e5+10;
int pre[2][3][N]={};
int n;
int dif[N]={};
map<char,int>d;
void init(string a,string b)
{
d['A']=0;d['C']=1;d['T']=2;
n=a.size();
for (int i=0;i<n;i++)
{
for (int j=0;j<3;j++)
pre[0][j][i+1]=pre[0][j][i];
pre[0][d[a[i]]][i+1]++;
}
for (int i=0;i<n;i++)
{
for (int j=0;j<3;j++)
pre[1][j][i+1]=pre[1][j][i];
pre[1][d[b[i]]][i+1]++;
}
for (int i=0;i<n;i++)
dif[i+1]=dif[i]+(a[i]!=b[i]);
}
int get_distance(int x, int y)
{
y++;
for (int i=0;i<3;i++)
{
if (pre[0][i][y]-pre[0][i][x]!=pre[1][i][y]-pre[1][i][x])
{
cout<<i<<'\n';
return -1;
}
}
return (dif[y]-dif[x]+1)/2;
}
