#include <bits/stdc++.h>
using namespace std;
string a,b;
int n;
int cntA[2][100005], cntC[2][100005], cntT[2][100005], pref[6][100005];
void init(string A, string B) {
a = A;
b = B;
n = a.length();
memset(pref,0,sizeof pref);
memset(cntA,0,sizeof cntA);
memset(cntC,0,sizeof cntC);
memset(cntT,0,sizeof cntT);
for(int i=0; i<n; i++) {
if(a[i] != b[i]) {
if(a[i] == 'A') {
if(b[i] == 'T')
pref[0][i]++;
else if(b[i] == 'C')
pref[1][i]++;
}
else if(a[i] == 'T') {
if(b[i] == 'A')
pref[2][i]++;
else if(b[i] == 'C')
pref[3][i]++;
}
else if(a[i] == 'C') {
if(b[i] == 'A')
pref[4][i]++;
else if(b[i] == 'T')
pref[5][i]++;
}
}
if(a[i] == 'A')
cntA[0][i]++;
else if(a[i] == 'C')
cntC[0][i]++;
else if(a[i] == 'T')
cntT[0][i]++;
if(b[i] == 'A')
cntA[1][i]++;
else if(b[i] == 'C')
cntC[1][i]++;
else if(b[i] == 'T')
cntT[1][i]++;
if(i) {
pref[0][i]+=pref[0][i-1];
pref[1][i]+=pref[1][i-1];
pref[2][i]+=pref[2][i-1];
pref[3][i]+=pref[3][i-1];
pref[4][i]+=pref[4][i-1];
pref[5][i]+=pref[5][i-1];
cntA[0][i]+=cntA[0][i-1];
cntC[0][i]+=cntC[0][i-1];
cntT[0][i]+=cntT[0][i-1];
cntA[1][i]+=cntA[1][i-1];
cntC[1][i]+=cntC[1][i-1];
cntT[1][i]+=cntT[1][i-1];
}
}
}
int get_distance(int x, int y) {
int numA[2], numC[2], numT[2];
numA[0] = cntA[0][y];
numC[0] = cntC[0][y];
numT[0] = cntT[0][y];
if(x) {
numA[0]-=cntA[0][x-1];
numC[0]-=cntC[0][x-1];
numT[0]-=cntT[0][x-1];
}
numA[1] = cntA[1][y];
numC[1] = cntC[1][y];
numT[1] = cntT[1][y];
if(x) {
numA[1]-=cntA[1][x-1];
numC[1]-=cntC[1][x-1];
numT[1]-=cntT[1][x-1];
}
if(numA[0] != numA[1] or numC[0] != numC[1] or numT[0] != numT[1])
return -1;
int cnt[6];
for(int i=0; i<6; i++)
cnt[i] = pref[i][y];
if(x)
for(int i=0; i<6; i++)
cnt[i]-=pref[i][x-1];
return (max(cnt[0],cnt[2])+max(cnt[1],cnt[4])+max(cnt[3],cnt[5]));
}
