#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= (a); i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)

#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound

#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rsz resize

const int MOD = 1000000007; // 998244353
const ll INF = 1e18;
const int MX = 200005;
const ld PI = 4*atan((ld)1);

template<class T> void ckmin(T &a, T b) { a = min(a, b); }
template<class T> void ckmax(T &a, T b) { a = max(a, b); }

namespace input {
    template<class T> void re(complex<T>& x);
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);

    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    void re(ld& x) { string t; re(t); x = stold(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) { 
        re(first); re(rest...); 
    }

    template<class T> void re(complex<T>& x) { T a,b; re(a,b); x = cd(a,b); }
    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}

using namespace input;

namespace output {
    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);

    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) { 
        pr(first); pr(rest...); 
    }

    template<class T1, class T2> void pr(const pair<T1,T2>& x) { 
        pr("{",x.f,", ",x.s,"}"); 
    }
    template<class T> void prContain(const T& x) {
        pr("{");
        bool fst = 1; for (const auto& a: x) pr(!fst?", ":"",a), fst = 0; // const needed for vector<bool>
        pr("}");
    }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }
    
    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) { 
        pr(first); ps(); // no space at end of line
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) { 
        pr(first," "); ps(rest...); // print w/ spaces
    }
}

using namespace output;

namespace io {
    void setIn(string s) { freopen(s.c_str(),"r",stdin); }
    void setOut(string s) { freopen(s.c_str(),"w",stdout); }
    void setIO(string s = "") {
        ios_base::sync_with_stdio(0); cin.tie(0); // fast I/O
        if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
    }
}

using namespace io;

template<class T> T invGeneral(T a, T b) {
    a %= b; if (a == 0) return b == 1 ? 0 : -1;
    T x = invGeneral(b,a); 
    return x == -1 ? -1 : ((1-(ll)b*x)/a+b)%b;
}

template<class T> struct modular {
    T val; 
    explicit operator T() const { return val; }
    modular() { val = 0; }
    modular(const ll& v) { 
        val = (-MOD <= v && v <= MOD) ? v : v % MOD;
        if (val < 0) val += MOD;
    }
    
    friend ostream& operator<<(ostream& os, const modular& a) { return os << a.val; }
    friend bool operator==(const modular& a, const modular& b) { return a.val == b.val; }
    friend bool operator!=(const modular& a, const modular& b) { return !(a == b); }
    friend bool operator<(const modular& a, const modular& b) { return a.val < b.val; }

    modular operator-() const { return modular(-val); }
    modular& operator+=(const modular& m) { if ((val += m.val) >= MOD) val -= MOD; return *this; }
    modular& operator-=(const modular& m) { if ((val -= m.val) < 0) val += MOD; return *this; }
    modular& operator*=(const modular& m) { val = (ll)val*m.val%MOD; return *this; }
    friend modular pow(modular a, ll p) {
        modular ans = 1; for (; p; p /= 2, a *= a) if (p&1) ans *= a;
        return ans;
    }
    friend modular inv(const modular& a) { 
        auto i = invGeneral(a.val,MOD); assert(i != -1);
        return i;
    } // equivalent to return exp(b,MOD-2) if MOD is prime
    modular& operator/=(const modular& m) { return (*this) *= inv(m); }
    
    friend modular operator+(modular a, const modular& b) { return a += b; }
    friend modular operator-(modular a, const modular& b) { return a -= b; }
    friend modular operator*(modular a, const modular& b) { return a *= b; }
    
    friend modular operator/(modular a, const modular& b) { return a /= b; }
};

typedef modular<int> mi;
typedef pair<mi,mi> pmi;
typedef vector<mi> vmi;
typedef vector<pmi> vpmi;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

string s;

string compress(string z) {
	string res;
    F0R(i,sz(z)) if (i == 0 || z[i] != z[i-1]) res += z[i];
    return res;
}

void init() {
    setIO(); 
    re(s); s = compress(s);
}

string swa(string a, char x, char y) {
	trav(t,a) {
		if (t == x) t = y;
		else if (t == y) t = x;
	}
	return a;
}

string finish(vector<string> v) {
	trav(t,v) t = compress(t);
	int des = sz(v)-1, b = 0, c = 0;
	trav(t,v) {
		trav(z,t) {
			if (z == 'B') b ++;
			else c++;
		}
	}
	F0R(i,sz(v)) {
		auto& t = v[i];
		if (b > c && sz(t) && t.back() == 'B' && (sz(t) > 1 || i == 0 || i == sz(v)-1)) {
			t.pop_back();
			b --;
		}
		if (b > c && sz(t) && t.front() == 'B' && (sz(t) > 1 || i == 0 || i == sz(v)-1)) {
			t.erase(t.begin());
			b --;
		}
		if (b < c && sz(t) && t.back() == 'C' && (sz(t) > 1 || i == 0 || i == sz(v)-1)) {
			t.pop_back();
			c --;
		}
		if (b < c && sz(t) && t.front() == 'C' && (sz(t) > 1 || i == 0 || i == sz(v)-1)) {
			t.erase(t.begin());
			c --;
		}
	}
	F0R(i,sz(v)) {
		auto& t = v[i];
		while (sz(t) >= 2 && (sz(t) > 2 || i == 0 || i == sz(v)-1) && b > sz(v)-1) {
			t.pop_back(), t.pop_back();
			b --, c --;
		}
	}
	assert(sz(v)-1 == b && sz(v)-1 == c);
	string res;
	F0R(i,sz(v)) {
		res += v[i];
		if (i != sz(v)-1) res += 'A';
	}
	return res;
	// ps("HUH",v,sz(v)-1,b,c); exit(0);
}

string solve(string s) {
	array<int,3> oc = array<int,3>();
	trav(t,s) oc[t-'A'] ++;
	if (oc[0] > oc[1]) {
		auto a = solve(swa(s,'A','B'));
		return swa(a,'A','B');
	}
	if (oc[0] > oc[2]) {
		auto a = solve(swa(s,'A','C'));
		return swa(a,'A','C');
	}
	int b1 = 0, b2 = 0, c1 = 0, c2 = 0;
	vector<string> v;
	for (int i = 0; i <= sz(s); ) {
		string t = "";
		while (i < sz(s) && s[i] != 'A') t += s[i++];
		i ++;
		v.pb(t);
	}
	trav(t,v) t = compress(t);
	F0R(i,sz(v)) {
		if (find(all(v[i]),'B') != v[i].end()) b1 ++;
		if (find(all(v[i]),'C') != v[i].end()) c1 ++;
		if (i != 0 && i != sz(v)-1) {
			if (v[i] == "B") b2 ++;
			if (v[i] == "C") c2 ++;
		}
	}
	if (b2 <= c1 && c2 <= b1) return finish(v);
	if (b2 > c1) {
		int dif = b2-c1;
		vector<string> V;
		F0R(i,sz(v)) {
			bool bad = 0;
			if (i != 0 && i != sz(v)-1 && v[i] == "B") bad = 1;
			if (bad && dif) {
				V.back() += v[i];
				dif --;
			} else V.pb(v[i]);
		}
		return finish(V);
	} else {
		assert(c2 > b1);
		int dif = c2-b1;
		vector<string> V;
		F0R(i,sz(v)) {
			bool bad = 0;
			if (i != 0 && i != sz(v)-1 && v[i] == "C") bad = 1;
			if (bad && dif) {
				V.back() += v[i];
				dif --;
			} else V.pb(v[i]);
		}
		return finish(V);
	}
}

int main() {
	init(); 
	ps(solve(s));
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?), set tle
    * do smth instead of nothing and stay organized
*/

Measured memory_bytes: 42736