#include <bits/stdc++.h>
#include "dna.h"
#define inf 1000000007
#define mod 1000000007
#define rnd() rand_num()
#define bigrnd() dis(rand_num)
//#pragma GCC optimize("Ofast","inline","-ffast-math")
//#pragma GCC target("avx,sse2,sse3,sse4,mmx")
//#define int long long
using namespace std;
unsigned sed=std::chrono::system_clock::now().time_since_epoch().count();
mt19937 rand_num(sed);
uniform_int_distribution<long long> dis(0,inf);
template <typename T> void read(T &x){
x=0;char ch=getchar();int fh=1;
while (ch<'0'||ch>'9'){if (ch=='-')fh=-1;ch=getchar();}
while (ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
x*=fh;
}
template <typename T> void write(T x) {
if (x<0) x=-x,putchar('-');
if (x>9) write(x/10);
putchar(x%10+'0');
}
template <typename T> void writeln(T x) {
write(x);
puts("");
}
int n;
char a[100005],b[100005];
int cnta[3][100005];
int cntb[3][100005];
int cnt[10][100005];
inline int get(char x,char y)
{
if(x=='A')
{
if(y=='A') return 1;
else if(y=='T') return 2;
else return 3;
}
else if(x=='T')
{
if(y=='A') return 4;
else if(y=='T') return 5;
else return 6;
}
else
{
if(y=='A') return 7;
else if(y=='T') return 8;
else return 9;
}
}
void init(string A,string B)
{
n=A.size();
for(int i=1;i<=n;++i)
{
a[i]=A[i-1];
b[i]=B[i-1];
}
for(int i=1;i<=n;++i)
{
cnta[0][i]=cnta[0][i-1]+(a[i]=='A'?1:0);
cnta[1][i]=cnta[1][i-1]+(a[i]=='T'?1:0);
cnta[2][i]=cnta[2][i-1]+(a[i]=='C'?1:0);
cntb[0][i]=cntb[0][i-1]+(b[i]=='A'?1:0);
cntb[1][i]=cntb[1][i-1]+(b[i]=='T'?1:0);
cntb[2][i]=cntb[2][i-1]+(b[i]=='C'?1:0);
for(int j=1;j<=9;++j)
if(j==get(a[i],b[i]))
cnt[j][i]=cnt[j][i-1]+1;
else
cnt[j][i]=cnt[j][i-1];
}
}
int get_distance(int x,int y)
{
x++,y++;
if(cnta[0][y]-cnta[0][x-1]!=cntb[0][y]-cntb[0][x-1]) return -1;
if(cnta[1][y]-cnta[1][x-1]!=cntb[1][y]-cntb[1][x-1]) return -1;
if(cnta[2][y]-cnta[2][x-1]!=cntb[2][y]-cntb[2][x-1]) return -1;
int ans=y-x+1,cur=y-x+1;
ans-=cnt[1][y]-cnt[1][x-1];
ans-=cnt[5][y]-cnt[5][x-1];
ans-=cnt[9][y]-cnt[9][y-1];
ans-=min(cnt[2][y]-cnt[2][x-1],cnt[4][y]-cnt[4][x-1]);
ans-=min(cnt[3][y]-cnt[3][x-1],cnt[7][y]-cnt[7][x-1]);
ans-=min(cnt[6][y]-cnt[6][x-1],cnt[8][y]-cnt[8][x-1]);
cur-=2*min(cnt[2][y]-cnt[2][x-1],cnt[4][y]-cnt[4][x-1]);
cur-=2*min(cnt[3][y]-cnt[3][x-1],cnt[7][y]-cnt[7][x-1]);
cur-=2*min(cnt[6][y]-cnt[6][x-1],cnt[8][y]-cnt[8][x-1]);
ans-=cur/3;
return ans;
}
