#include "dna.h"
#include <bits/stdc++.h>
using namespace std ;
const int N = 1e5 + 5 ;
int a[N] , t[N] , c[N] , a1[N] , t1[N] , c1[N] ;
int pref[N] ;
void init( string x , string y ) {
int n = x.size() ;
for ( int i = 0 ; i < n ; i ++ ){
pref[i] = ( x[i] != y[i] ) ;
a[i] = ( x[i] == 'A' ) ;
c[i] = ( x[i] == 'C' ) ;
t[i] = ( x[i] == 'T' ) ;
a1[i] = ( y[i] == 'A' ) ;
c1[i] = ( y[i] == 'C' ) ;
t1[i] = ( y[i] == 'T' ) ;
if (i){
pref[i] += pref[i-1] ;
a[i] += a[i-1] ;
c[i] += c[i-1] ;
t[i] += t[i-1] ;
a1[i] += a1[i-1] ;
c1[i] += c1[i-1] ;
t1[i] += t1[i-1] ;
}
}
}
int get_distance(int x, int y) {
int d = pref[y] ;
if (x) d -= pref[x-1] ;
int sum = ( a[y] - a[x-1] ) - ( a1[y] - a1[x-1] ) ;
if (sum!=0) return -1 ;
sum = ( c[y] - c[x-1] ) - ( c1[y] - c1[x-1] ) ;
if (sum!=0) return -1 ;
sum = ( t[y] - t[x-1] ) - ( t1[y] - t1[x-1] ) ;
if (sum!=0) return -1 ;
return (d+1)/2 ;
}
