//Author:xht37
#include <bits/stdc++.h>

#define ui unsigned int
#define ll long long
#define ul unsigned ll
#define ld long double

#define pi pair <int, int>
#define fi first
#define se second
#define mp make_pair

#define ls (p << 1)
#define rs (ls | 1)
#define md ((t[p].l + t[p].r) >> 1)

#define vi vector <int>
#define pb push_back
#define pq priority_queue

#define dbg(x) cerr << #x" = " << x << endl
#define debug(...) fprintf(stderr, __VA_ARGS__)

#define fl(x) freopen(x".in", "r", stdin), freopen(x".out", "w", stdout)

using namespace std;

namespace io {
	const int SI = 1 << 21 | 1;
	char IB[SI], *IS, *IT, OB[SI], *OS = OB, *OT = OS + SI - 1, c, ch[100];
	int f, t;
	#define gc() (IS == IT ? (IT = (IS = IB) + fread(IB, 1, SI, stdin), IS == IT ? EOF : *IS++) : *IS++)
	inline void flush() {
		fwrite(OB, 1, OS - OB, stdout), OS = OB;
	}
	inline void pc(char x) {
		*OS++ = x;
		if (OS == OT) flush();
	}

	template <class I>
	inline void rd(I &x) {
		for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;
		for (x = 0; c >= '0' && c <= '9'; x = (x << 3) + (x << 1) + (c & 15), c = gc());
		x *= f;
	}
	template <class I>
	inline void rd(I &x, I &y) {
		rd(x), rd(y);
	}
	template <class I>
	inline void rd(I &x, I &y, I &z) {
		rd(x), rd(y), rd(z);
	}
	template <class I>
	inline void rda(I *a, int n) {
		for (int i = 1; i <= n; i++) rd(a[i]);
	}
	inline void rdc(char &c) {
		for (c = gc(); c < 33 || c > 126; c = gc());
	}
	inline void rds(char *s, int &n) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (n = 0; c >= 33 && c <= 126; s[++n] = c, c = gc());
		s[n+1] = '\0';
	}
	inline void rds(string &s) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (s.clear(); c >= 33 && c <= 126; s.pb(c), c = gc());
	}

	template <class I>
	inline void print(I x, char k = '\n') {
		if (!x) pc('0');
		if (x < 0) pc('-'), x = -x;
		while (x) ch[++t] = x % 10 + '0', x /= 10;
		while (t) pc(ch[t--]);
		pc(k);
	}
	template <class I>
	inline void print(I x, I y) {
		print(x, ' '), print(y);
	}
	template <class I>
	inline void print(I x, I y, I z) {
		print(x, ' '), print(y, ' '), print(z);
	}
	template <class I>
	inline void printa(I *a, int n) {
		for (int i = 1; i <= n; i++) print(a[i], " \n"[i==n]);
	}
	inline void printc(char c) {
		pc(c);
	}
	inline void prints(char *s, int n) {
		for (int i = 1; i <= n; i++) pc(s[i]);
		pc('\n');
	}
	inline void prints(string s) {
		int n = s.length();
		while (t < n) pc(s[t++]);
		pc('\n'), t = 0;
	}
	struct Flush {
		~Flush() {
			flush();
		}
	} flusher;
}
using io::rd;
using io::rda;
using io::rdc;
using io::rds;
using io::print;
using io::printa;
using io::printc;
using io::prints;

const int N = 1e6 + 7;
int n, t[3];
char s[N], c[3];
set<int> p;

inline void del(int x, int c) {
	p.erase(x), --t[c];
}

int main() {
	rds(s, n);
	for (int i = 0; i < 3; i++) c[i] = 'A' + i;
	for (int i = 1; i <= n; i++)
		if (s[i] != s[i+1]) p.insert(i), ++t[s[i]-'A'];
	if (t[1] > t[2]) swap(t[1], t[2]), swap(c[1], c[2]);
	if (t[0] > t[1]) swap(t[0], t[1]), swap(c[0], c[1]);
	if (t[1] > t[2]) swap(t[1], t[2]), swap(c[1], c[2]);
//	for (int i = 0; i < 3; i++)
//		debug("%c %d\n", c[i], t[i]);
	int c1 = 0, c2 = 0, c3 = 0, o1 = 0, o2 = 0;
	for (int x : p)
		if (s[x] == c[0]) {
			if (o1 && o2) ++c1;
			else if (o1) ++c2;
			else if (o2) ++c3;
			o1 = o2 = 0;
		} else if (s[x] == c[1]) o1 = 1;
		else o2 = 1;
	if (o1 && o2) ++c1;
	else if (o1) ++c2;
	else if (o2) ++c3;
	o1 = o2 = 0;
//	debug("%d %d %d\n", c1, c2, c3);
	if (c1 + c2 < c3) {
		if (s[*p.begin()] == c[2] && s[*++p.begin()] == c[0])
			del(*p.begin(), 2), --c3;
		if (c1 + c2 < c3) {
			if (s[*--p.end()] == c[2] && s[*--(--p.end())] == c[0])
				del(*--p.end(), 2), --c3;
			if (c1 + c2 < c3)
				for (int x : p)
					if (s[x] == c[0]) {
						if (o1 && o2) {
							del(o1, 0), del(o2, 2);
//							dbg(o1);
							o1 = x, o2 = 0;
							if (c1 + c2 == --c3) break;
						} else o1 = x, o2 = 0;
					} else if (s[x] == c[1]) o1 = 0, o2 = 0;
					else if (s[x] == c[2]) {
						if (o1 && !o2) o2 = x;
						else o1 = 0, o2 = 0;
					}
		}
	}
//	debug("%d %d %d\n", t[0], t[1], t[2]);
	if (t[1] < t[2]) {
		auto it = p.begin();
		while (it != p.end()) {
			auto itl = it, itr = it;
			if (s[*it] != c[2] || !(it == p.begin() || ++itr == p.end() || s[*--itl] != s[*itr])) {
				++it;
				continue;
			}
//			dbg(*it);
			del(*it++, 2);
			if (t[1] == t[2]) break;
		}
	}
//	debug("%d %d %d\n", t[0], t[1], t[2]);
	if (t[0] < t[1]) {
		auto it = p.begin();
		while (it != p.end()) {
			auto itl = it, itr = it, itrr = it;
			if (s[*it] == c[0] || ++itr == p.end() || s[*itr] == c[0] || s[*it] == s[*itr] || !(it == p.begin() || (itrr = itr, ++itrr) == p.end() || s[*--itl] != s[*itrr])) {
				++it;
				continue;
			}
			int x = s[*it] == c[1] ? 1 : 2, y = x == 1 ? 2 : 1;
			del(*it++, x), del(*it++, y);
			if (t[0] == t[1]) break;
		}
	}
	for (int x : p) printc(s[x]);
	return 0;
}

Measured memory_bytes: 53364