#include "dna.h"
#include<bits/stdc++.h>
using namespace std;
int n, cd[100005][3][3];
void init(string a, string b) {
memset(cd, 0, sizeof(cd));
n = a.size(); a = '&' + a; b = '&' + b;
for(int i = 1; i <= n; i++){
int x, y;
if(a[i] == 'A') x = 0;
else if(a[i] == 'C') x = 1;
else x = 2;
if(b[i] == 'A') y = 0;
else if(b[i] == 'C') y = 1;
else y = 2;
cd[i][x][y] = 1;
for(int j = 0; j < 3; j++){
for(int k = 0; k < 3; k++){
cd[i][j][k] += cd[i-1][j][k];
}
}
}
}
int get_distance(int l, int r) {
int c[3][3]; l++; r++;
for(int i = 0; i < 3; i++){
for(int j = 0; j < 3; j++) c[i][j] = cd[r][i][j] - cd[l-1][i][j];
}
int ans = 0;
int add = min(c[0][1], c[1][0]); ans += add;
c[0][1] -= add; c[1][0] -= add;
add = min(c[1][2], c[2][1]); ans += add;
c[1][2] -= add; c[2][1] -= add;
add = min(c[0][2], c[2][0]); ans += add;
c[0][2] -= add; c[2][0] -= add;
if(c[0][1] != c[1][2] || c[1][2] != c[2][3] || c[1][0] != c[0][2] || c[0][2] != c[2][1]) return -1;
ans += (c[0][1] + c[1][0]) * 2;
return ans;
}
