#include <algorithm>
#include <array>
#include <string>
#include <vector>
auto pfxs = std::vector<std::array<std::array<int, 3>, 3>>();
auto get_distance(int x, int y) -> int {
auto cnts = std::array<std::array<int, 3>, 3>();
auto diffs = std::array<int, 3>();
for (auto i = 0; i < 3; ++i) {
for (auto j = 0; j < 3; ++j) {
cnts[i][j] = pfxs[y + 1][i][j] - pfxs[x][i][j];
diffs[i] += cnts[i][j];
diffs[j] -= cnts[i][j];
}
}
if (std::count(std::begin(diffs), std::end(diffs), 0) < 3) {
return -1;
}
auto dist = 0;
auto rem = 0;
for (auto i = 0; i < 3; ++i) {
for (auto j = i + 1; j < 3; ++j) {
const auto mn = std::min(cnts[i][j], cnts[j][i]);
dist += mn;
cnts[i][j] -= mn;
cnts[j][i] -= mn;
rem += cnts[i][j] + cnts[j][i];
}
}
dist += rem / 3 * 2;
return dist;
}
auto init(std::string a, std::string b) -> void {
const auto n = static_cast<int>(std::size(a));
pfxs.resize(n + 1);
for (auto i = 0; i < n; ++i) {
pfxs[i + 1] = pfxs[i];
const auto conv = [](char type) {
if (type == 'A') {
return 0;
}
return type == 'C' ? 1 : 2;
};
++pfxs[i + 1][conv(a[i])][conv(b[i])];
}
}
