#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
vector<int> a;
vector<int> b;
int n;
int char_to_num(char c) {
if (c == 'A') {
return 0;
}
if (c == 'C') {
return 1;
}
return 2;
}
void init(string A, string B) {
n = A.size();
for (int i = 0; i < n; i++) {
a.push_back(char_to_num(A[i]));
b.push_back(char_to_num(B[i]));
}
}
int get_distance(int x, int y) {
vector<int> num(9);
for (int i = x; i <= y; i++) {
//printf("%d %d\n", a[i], b[i]);
num[a[i]*3+b[i]]++;
}
if (!(num[0]+num[3]+num[6] == num[0]+num[1]+num[2] && num[1]+num[4]+num[7] == num[3]+num[4]+num[5])) {
return -1;
}
int swaps = 0;
int ac = min(num[1], num[3]);
swaps += ac;
num[1] -= ac;
num[3] -= ac;
int at = min(num[2], num[6]);
swaps += at;
num[2] -= at;
num[6] -= at;
int ct = min(num[5], num[7]);
swaps += ct;
num[5] -= ct;
num[7] -= ct;
int s = num[1]+num[3]+num[2]+num[6]+num[5]+num[7];
swaps += (s/3)*2;
return swaps;
}
