#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int MXN = 1e5+5;
int A[MXN], C[MXN], T[MXN], AC[MXN], CA[MXN], AT[MXN], TA[MXN], CT[MXN], TC[MXN];
void init(string a, string b) {
for(int i=0; i<a.size(); i++) {
A[i+1] = A[i] + (a[i]=='A') - (b[i]=='A');
C[i+1] = C[i] + (a[i]=='C') - (b[i]=='C');
T[i+1] = T[i] + (a[i]=='T') - (b[i]=='T');
AC[i+1] = AC[i] + (a[i]=='A'&&b[i]=='C');
CA[i+1] = CA[i] + (a[i]=='C'&&b[i]=='A');
AT[i+1] = AT[i] + (a[i]=='A'&&b[i]=='T');
TA[i+1] = TA[i] + (a[i]=='T'&&b[i]=='A');
CT[i+1] = CT[i] + (a[i]=='C'&&b[i]=='T');
TC[i+1] = TC[i] + (a[i]=='T'&&b[i]=='C');
}
}
int get_distance(int x, int y) {
if(A[y+1]-A[x] || C[y+1]-C[x] || T[y+1]-T[x]) return -1;
int ac = AC[y+1]-AC[x];
int ca = CA[y+1]-CA[x];
int at = AT[y+1]-AT[x];
int ta = TA[y+1]-TA[x];
int ct = CT[y+1]-CT[x];
int tc = TC[y+1]-TC[x];
int tmp = min(ac, ca);
int res = tmp;
ac -= tmp;
ca -= tmp;
tmp = min(at, ta);
res += tmp;
at -= tmp;
ta -= tmp;
tmp = min(ct, tc);
res += tmp;
ct -= tmp;
tc -= tmp;
return res + 2*max({ac, ca, at, ta, ct, tc});
}
