#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int maxn=1e5+5;
int p1[maxn][3];
int p2[maxn][3];
int p3[maxn][3][3];
int s1[maxn];
int s2[maxn];
void init(std::string a, std::string b)
{
memset(p1,0,sizeof(p1));
memset(p2,0,sizeof(p2));
memset(p3,0,sizeof(p3));
for(int i=0;i<a.size();i++)
{
if(a[i]=='A')s1[i]=0;
else if(a[i]=='C')s1[i]=1;
else s1[i]=2;
if(b[i]=='A')s2[i]=0;
else if(b[i]=='C')s2[i]=1;
else s2[i]=2;
}
p1[0][s1[0]]++;
p2[0][s2[0]]++;
p3[0][s1[0]][s2[0]]++;
for(int i=1;i<a.size();i++)
{
for(int t1=0;t1<=2;t1++)
{
for(int t2=0;t2<=2;t2++)
{
p3[i][t1][t2]=p3[i-1][t1][t2];
}
p1[i][t1]=p1[i-1][t1];
p2[i][t1]=p2[i-1][t1];
}
p3[i][s1[i]][s2[i]]++;
p1[i][s1[i]]++;
p2[i][s2[i]]++;
}
}
int c[3][3];
int get_distance(int x, int y)
{
if(x==0&&(p1[y][0]!=p2[y][0]||p1[y][1]!=p2[y][1]||p1[y][2]!=p2[y][2])|| x!=0&&
(p1[y][0]-p1[x-1][0]!=p2[y][0]-p2[x-1][0]||p1[y][1]-p1[x-1][1]!=p2[y][1]-p2[x-1][1]||p1[y][2]-p1[x-1][2]!=p2[y][2]-p2[x-1][2]))return -1;
for(int i=0;i<=2;i++)
{
for(int j=0;j<=2;j++)
{
if(x==0)c[i][j]=p3[y][i][j];
else c[i][j]=p3[y][i][j]-p3[x-1][i][j];
}
}
int ans=0;
int all=y-x+1;
all-=c[0][0];
all-=c[1][1];
all-=c[2][2];
int h=min(c[0][1],c[1][0]);
ans+=h;
all-=h*2;
h=min(c[0][2],c[2][0]);
ans+=h;
all-=h*2;
h=min(c[1][2],c[2][1]);
ans+=h;
all-=h*2;
ans+=(all/3)*2;
return ans;
}
