#include <bits/stdc++.h>
#include "dna.h"
using namespace std;
#define lim 100005
int n;
int pre_a_a[lim],pre_b_a[lim];// a string a char ----- b string a char
int pre_a_t[lim],pre_b_t[lim];// a string t char ----- b string t char
int pre_a_c[lim],pre_b_c[lim];// a string c char ----- b string c char
int at[lim],ta[lim],ac[lim],ca[lim],tc[lim],ct[lim];
int sum[lim];
inline bool querya(int x,int y){
if(pre_a_a[y+1]-pre_a_a[x]==pre_b_a[y+1]-pre_b_a[x])return 1;
return 0;
}
inline bool queryt(int x,int y){
if(pre_a_t[y+1]-pre_a_t[x]==pre_b_t[y+1]-pre_b_t[x])return 1;
return 0;
}
inline bool queryc(int x,int y){
if(pre_a_c[y+1]-pre_a_c[x]==pre_b_c[y+1]-pre_b_c[x])return 1;
return 0;
}
void init(string a,string b) {
n=a.length();
for(int i=0;i<n;i++){
pre_a_a[i+1]=pre_a_a[i];
if(a[i]=='A')pre_a_a[i+1]++;
pre_b_a[i+1]=pre_b_a[i];
if(b[i]=='A')pre_b_a[i+1]++;
pre_a_t[i+1]=pre_a_t[i];
if(a[i]=='T')pre_a_t[i+1]++;
pre_b_t[i+1]=pre_b_t[i];
if(b[i]=='T')pre_b_t[i+1]++;
pre_a_c[i+1]=pre_a_c[i];
if(a[i]=='C')pre_a_c[i+1]++;
pre_b_c[i+1]=pre_b_c[i];
if(b[i]=='C')pre_b_c[i+1]++;
sum[i+1]=sum[i];
if(a[i]!=b[i])sum[i+1]++;
ac[i+1]=ac[i],at[i+1]=at[i];
ca[i+1]=ca[i],ct[i+1]=ct[i];
ta[i+1]=ta[i],tc[i+1]=tc[i];
if(a[i]=='A'){
if(b[i]=='C')ac[i+1]++;
else if(b[i]=='T')at[i+1]++;
}
else if(a[i]=='C'){
if(b[i]=='A')ca[i+1]++;
else if(b[i]=='T')ct[i+1]++;
}
else{
if(b[i]=='A')ta[i+1]++;
else if(b[i]=='C')tc[i+1]++;
}
}
}
int get_distance(int x, int y) {
if(querya(x,y) && queryt(x,y) && queryc(x,y)){
int cev=0;
int anormal=sum[y+1]-sum[x];
cev+=min(at[y+1]-at[x],ta[y+1]-ta[x]);
cev+=min(ac[y+1]-ac[x],ca[y+1]-ca[x]);
cev+=min(tc[y+1]-tc[x],ct[y+1]-ct[x]);
anormal-=cev*2;
cev+=(anormal/3)*2;
return cev;
}
else return -1;
}
