#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
using ll = long long;
using ii = pair<int,int>;
const int INF = 1e9;
const ll LLINF = 1e18;
using vi = vector<int>;
using vvi = vector<vi>;
struct dna {
int ac, at, ca, ct, ta, tc;
};
int n;
vector<dna> pos, pre;
void init (string a, string b) {
n = a.size();
pos = vector<dna>(n);
for (int i = 0; i < n; i++) {
if (a[i] == 'A' and b[i] == 'C') pos[i].ac = 1;
if (a[i] == 'A' and b[i] == 'T') pos[i].at = 1;
if (a[i] == 'C' and b[i] == 'A') pos[i].ca = 1;
if (a[i] == 'C' and b[i] == 'T') pos[i].ct = 1;
if (a[i] == 'T' and b[i] == 'A') pos[i].ta = 1;
if (a[i] == 'T' and b[i] == 'C') pos[i].tc = 1;
}
pre = vector<dna>(n+1);
pre[0].ac = pre[0].at = pre[0].ca = pre[0].ct = pre[0].ta = pre[0].tc = 0;
for (int i = 0; i < n; i++) {
pre[i+1].ac = pre[i].ac + pos[i].ac;
pre[i+1].at = pre[i].at + pos[i].at;
pre[i+1].ca = pre[i].ca + pos[i].ca;
pre[i+1].ct = pre[i].ct + pos[i].ct;
pre[i+1].ta = pre[i].ta + pos[i].ta;
pre[i+1].tc = pre[i].tc + pos[i].tc;
}
}
int get_distance (int x, int y) {
y++;
int AC = pre[y].ac - pre[x].ac;
int AT = pre[y].at - pre[x].at;
int CA = pre[y].ca - pre[x].ca;
int CT = pre[y].ct - pre[x].ct;
int TA = pre[y].ta - pre[x].ta;
int TC = pre[y].tc - pre[x].tc;
int ans = 0, res;
res = min(AC, CA);
ans += res;
AC -= res; CA -= res;
res = min(AT, TA);
ans += res;
AT -= res; TA -= res;
res = min(CT, TC);
ans += res;
CT -= res; TC -= res;
if (AC == CT and CT == TA) {
ans += 2*AC;
AC = CT = TA = 0;
}
if (AT == TC and TC == CA) {
ans += 2*AT;
AT = TC = CA = 0;
}
if (AC + AT + CA + CT + TA + TC > 0) return -1;
return ans;
}
// int main() {
// init("ATACAT", "ACTATA");
// cout << get_distance(1, 3) << '\n';
// }
