#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
int n, dp[100010][3][3];
void init(string a, string b) {
n = a.size();
for(int i=1; i<=n; i++) {
int x, y;
if(a[i-1] == 'C') x = 0;
else if(a[i-1] == 'A') x = 1;
else x = 2;
if(b[i-1] == 'C') y = 0;
else if(b[i-1] == 'A') y = 1;
else y = 2;
dp[i][x][y]++;
for(int j=0; j<3; j++) {
for(int k=0; k<3; k++) {
dp[i][j][k] += dp[i-1][j][k];
}
}
}
}
int get_distance(int x, int y) {
x++; y++;
int ans = 0;
int ca = dp[y][0][1]-dp[x-1][0][1], ac = dp[y][1][0]-dp[x-1][1][0], ct = dp[y][0][2]-dp[x-1][0][2], tc = dp[y][2][0]-dp[x-1][2][0], at = dp[y][1][2]-dp[x-1][1][2], ta = dp[y][2][1]-dp[x-1][2][1];
if(at+ac-ta-tc != 0 || tc+ta-at-ac != 0 || ca+ct-tc-ta != 0) return -1;
int t = min(ta, at);
ans += t; ta -= t; at -= t;
t = min(ac, ca);
ans += t; ac -= t; ca -= t;
t = min(ct, tc);
ans += t; ct -= t; tc -= t;
ans += ((ac+at+ca+ct+ta+tc)*2)/3;
return ans;
}
