#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int n , psum[N][3][3] , suma[N][3] , sumb[N][3];
string a , b;
int f(char c)
{
if(c == 'A')
return 0;
else if(c == 'C')
return 1;
else
return 2;
}
void init(string aa, string bb) {
n = aa.size();
a = aa;
b = bb;
suma[0][f(a[0])] = 1;
sumb[0][f(b[0])] = 1;
psum[0][f(a[0])][f(b[0])] = 1;
for(int i = 1 ; i < n ; i++)
{
for(int j = 0 ; j < 3 ; j++)
{
suma[i][j] = suma[i - 1][j];
sumb[i][j] = sumb[i - 1][j];
for(int k = 0 ; k < 3 ; k++)
psum[i][j][k] = psum[i - 1][j][k];
}
suma[i][f(a[i])]++;
sumb[i][f(b[i])]++;
psum[i][f(a[i])][f(b[i])]++;
}
}
int get_distance(int x, int y) {
int cnt[3][3];
int ca[3] , cb[3];
for(int i = 0 ; i < 3 ; i++)
{
ca[i] = suma[y][i];
cb[i] = sumb[y][i];
for(int j = 0 ; j < 3 ; j++)
cnt[i][j] = psum[y][i][j];
}
if(x > 0)
{
for(int i = 0 ; i < 3 ; i++)
{
ca[i] -= suma[x - 1][i];
cb[i] -= sumb[x - 1][i];
for(int j = 0 ; j < 3 ; j++)
cnt[i][j] -= psum[x - 1][i][j];
}
}
for(int i = 0 ; i < 3 ; i++) if(ca[i] != cb[i])
return -1;
int ans = 0;
for(int i = 0 ; i < 2 ; i++) for(int j = i + 1 ; j < 3 ; j++)
{
int mn = min(cnt[i][j] , cnt[j][i]);
cnt[i][j] -= mn;
cnt[j][i] -= mn;
ans += mn;
}
for(int i = 0 ; i < 2 ; i++)
{
ans += cnt[i][2];
ans += cnt[2][i];
}
return ans;
}
