#include "dna.h"
#include <vector>
using namespace std;
const int MAXN = 1e5 + 123;
int pfbad_[MAXN];
int* pfbad;
int pfcnt__[MAXN][3];
int* pfcnt_[MAXN];
int** pfcnt = (pfcnt_ + 1);
vector<int> cnvt(string a){
int n = a.size();
vector<int> ans(n);
for(int i = 0; i < n; ++i){
if(a[i] == 'A')
ans[i] = 0;
if(a[i] == 'C')
ans[i] = 1;
if(a[i] == 'T')
ans[i] = 2;
}
return ans;
}
void init(string a_, string b_){
for(int i = 0; i < MAXN; ++i)
pfcnt_[i] = pfcnt__[i];
pfcnt = pfcnt_ + 1;
pfbad = pfbad_ + 1;
vector<int> a = cnvt(a_);
vector<int> b = cnvt(b_);
int n = a.size();
for(int i = 0; i < n; ++i){
pfbad[i] = pfbad[i - 1];
for(int j = 0; j < 3; ++j){
pfcnt[i][j] = pfcnt[i - 1][j];
}
if(a[i] != b[i]){
++pfbad[i];
++pfcnt[i][a[i]];
--pfcnt[i][b[i]];
}
}
}
int get_distance(int x, int y) {
++y;
for(int i = 0; i < 3; ++i){
if(pfcnt[y - 1][i] - pfcnt[x - 1][i] != 0)
return -1;
}
return max(pfbad[y - 1] - pfbad[x - 1] - 1, 0);
}
