#include<bits/stdc++.h>
#include "dna.h"
using namespace std;
const int maxn = 1e5;
int dif[maxn + 1], AinT[maxn + 1], aa[maxn + 1], at[maxn + 1], ba[maxn + 1], bt[maxn + 1];
int get_distance(int l, int r){
l++; r++;
if ((aa[r] - aa[l - 1]) != (ba[r] - ba[l - 1])) return -1;
if ((bt[r] - bt[l - 1]) != (at[r] - at[l - 1])) return -1;
int res = dif[r] - dif[l - 1];
res += (AinT[r] - AinT[l - 1]);
return res;
}
void init(string a, string b){
a = " " + a;
b = " " + b;
for (int i = 0; i < a.size(); ++i){
if (a[i] == 'A' && a[i] != b[i]) dif[i]++;
if (a[i] == 'T' && b[i] == 'C') dif[i]++;
dif[i] += dif[i - 1];
AinT[i] = AinT[i - 1] + (a[i] == 'A' && b[i] == 'C');
aa[i] = aa[i - 1] + (a[i] == 'A');
at[i] = at[i - 1] + (a[i] == 'T');
ba[i] = ba[i - 1] + (b[i] == 'A');
bt[i] = bt[i - 1] + (b[i] == 'T');
}
return;
}
