#include <bits/stdc++.h>
#include "dna.h"
#define DIM 100010
using namespace std;
struct segment_tree{
int stare[7];
} aint[DIM*4],sol;
string a,b;
int sp_a0[DIM],sp_a1[DIM],sp_a2[DIM],sp_b0[DIM],sp_b1[DIM],sp_b2[DIM];
int n;
void build (int nod, int st, int dr){
if (st == dr){
if (a[st-1] == 'A' && b[st-1] == 'C')
aint[nod].stare[1] = 1;
if (a[st-1] == 'A' && b[st-1] == 'T')
aint[nod].stare[2] = 1;
if (a[st-1] == 'C' && b[st-1] == 'A')
aint[nod].stare[3] = 1;
if (a[st-1] == 'C' && b[st-1] == 'T')
aint[nod].stare[4] = 1;
if (a[st-1] == 'T' && b[st-1] == 'A')
aint[nod].stare[5] = 1;
if (a[st-1] == 'T' && b[st-1] == 'C')
aint[nod].stare[6] = 1;
return;
}
int mid = (st+dr)>>1;
build (nod<<1,st,mid);
build ((nod<<1)|1,mid+1,dr);
for (int i=1;i<=6;i++)
aint[nod].stare[i] = aint[nod<<1].stare[i] + aint[(nod<<1)|1].stare[i];
}
void query (int nod, int st, int dr, int x, int y){
if (x <= st && dr <= y){
for (int i=1;i<=6;i++)
sol.stare[i] += aint[nod].stare[i];
return;
}
int mid = (st+dr)>>1;
if (x <= mid)
query (nod<<1,st,mid,x,y);
if (y > mid)
query ((nod<<1)|1,mid+1,dr,x,y);
}
void init (string A, string B){
n = A.size();
a = A, b = B;
build (1,1,n);
for (int i=1;i<=n;i++){
sp_a0[i] = sp_a0[i-1] + (a[i-1] == 'A');
sp_a1[i] = sp_a1[i-1] + (a[i-1] == 'C');
sp_a2[i] = sp_a2[i-1] + (a[i-1] == 'T');
sp_b0[i] = sp_b0[i-1] + (b[i-1] == 'A');
sp_b1[i] = sp_b1[i-1] + (b[i-1] == 'C');
sp_b2[i] = sp_b2[i-1] + (b[i-1] == 'T');
}
}
int get_distance (int x, int y){
x++, y++;
int ans = 0;
if (sp_a0[y] - sp_a0[x-1] != sp_b0[y] - sp_b0[x-1])
return -1;
if (sp_a1[y] - sp_a1[x-1] != sp_b1[y] - sp_b1[x-1])
return -1;
if (sp_a2[y] - sp_a2[x-1] != sp_b2[y] - sp_b2[x-1])
return -1;
for (int i=1;i<=6;i++)
sol.stare[i] = 0;
query (1,1,n,x,y);
int nr = min (sol.stare[1],sol.stare[3]);
ans += nr;
sol.stare[1] -= nr, sol.stare[3] -= nr;
nr = min (sol.stare[2],sol.stare[5]);
ans += nr;
sol.stare[2] -= nr, sol.stare[5] -= nr;
nr = min (sol.stare[4],sol.stare[6]);
ans += nr;
sol.stare[4] -= nr, sol.stare[6] -= nr;
nr = min (sol.stare[1],min(sol.stare[4],sol.stare[5]));
ans += 2 * nr;
sol.stare[1] -= nr, sol.stare[4] -= nr, sol.stare[5] -= nr;
nr = min (sol.stare[2],min(sol.stare[3],sol.stare[6]));
ans += 2 * nr;
sol.stare[2] -= nr, sol.stare[3] -= nr, sol.stare[6] -= nr;
return ans;
}
