#include "dna.h"
#include<bits/stdc++.h>
using namespace std;
vector<int> AC, AT, CA, CT, TA, TC;
void init(string a, string b) {
int n = a.size();
AC.resize(n+1);
AT.resize(n+1);
CA.resize(n+1);
CT.resize(n+1);
TA.resize(n+1);
TC.resize(n+1);
for (int i = 0; i < n; i++) {
AC[i+1] = AC[i] + (a[i] == 'A' && b[i] == 'C');
AT[i+1] = AT[i] + (a[i] == 'A' && b[i] == 'T');
CA[i+1] = CA[i] + (a[i] == 'C' && b[i] == 'A');
CT[i+1] = CT[i] + (a[i] == 'C' && b[i] == 'T');
TA[i+1] = TA[i] + (a[i] == 'T' && b[i] == 'A');
TC[i+1] = TC[i] + (a[i] == 'T' && b[i] == 'C');
}
}
int get_distance(int x, int y) {
int ac = AC[y + 1] - AC[x];
int at = AT[y + 1] - AT[x];
int ca = CA[y + 1] - CA[x];
int ct = CT[y + 1] - CT[x];
int ta = TA[y + 1] - TA[x];
int tc = TC[y + 1] - TC[x];
if (ac + at != ca + ta || ca + ct != ac + tc || ta + tc != at + ct) {
return -1;
}
int swap1 = min(ac, ca); ac -= swap1; ca -= swap1;
int swap2 = min(at, ta); at -= swap2; ta -= swap2;
int swap3 = min(ct, tc); ct -= swap3; tc -= swap3;
int cycle = ac + ca;
int ans = swap1 + swap2 + swap3 + 2 * cycle;
return ans;
}
