#include<bits/stdc++.h>
#include "dna.h"
using namespace std;
int n;
vector<vector<int>> freq, freq1;
vector<vector<int>> mis;
void init(std::string a, std::string b) {
n=a.length();
freq=vector<vector<int>>(n+1,vector<int>(2,0));
freq1=vector<vector<int>>(n+1,vector<int>(2,0));
mis=vector<vector<int>>(4,vector<int>(n+1,0));
for(int i=1;i<n+1;++i){
freq[i][0]=freq[i-1][0];
freq[i][1]=freq[i-1][1];
freq1[i][0]=freq1[i-1][0];
freq1[i][1]=freq1[i-1][1];
if(a[i-1]=='A') freq[i][0]++;
if(b[i-1]=='A') freq[i][1]++;
if(a[i-1]=='T') freq1[i][0]++;
if(b[i-1]=='T') freq1[i][1]++;
for(int j=0;j<4;++j) mis[j][i]=mis[j][i-1];
if(a[i-1]!=b[i-1]){
mis[0][i]+=(b[i-1]=='A');
mis[1][i]+=(b[i-1]=='T');
mis[2][i]+=(b[i-1]=='T' && a[i-1]=='A');
mis[3][i]+=(b[i-1]=='A' && a[i-1]=='T');
}
}
}
int get_distance(int x, int y) {
y++;
if(freq[y][0]-freq[x][0]!=freq[y][1]-freq[x][1] || freq1[y][0]-freq1[x][0]!=freq1[y][1]-freq1[x][1]) return -1;
int a=mis[0][y]-mis[0][x], t=mis[1][y]-mis[1][x], ta=mis[2][y]-mis[2][x], at=mis[3][y]-mis[3][x];
return a+t-min(at,ta);
}
