URI Zero or One

 // Accepted

/// Header file begin
#include <iostream>
#include <cstdio>
#include <cstring>
#include <map>
#include <string>
#include <vector>
#include <cmath>
#include <cctype>
#include <sstream>
#include <set>
#include <list>
#include <stack>
#include<utility>
#include <queue>
#include <algorithm>
/// End
//..........
/// Macro
#define sf scanf
#define pf printf
#define sfint(a,b) scanf("%d %d",&a,&b)
#define sfl(a,b) scanf("%ld %ld",&a,&b)
#define sfll(a,b) scanf("%lld %lld",&a,&b)
#define sfd(a,b) scanf("%lf %lf",&a,&b)
#define sff(a,b) scanf("%f %f",&a,&b)
#define lp1(i,n) for(i=0;i<n;i++)
#define lp2(i,n) for(i=1;i<=n;i++)
#define mem(c,v) memset(c,v,sizeof(c))
#define cp(a) cout<<" "<<a<<" "
#define nl puts("")
#define sq(x) ((x)*(x))
#define all(x) x.begin(),x.end()
#define reall(x) x.rbegin(),x.rend()
#define sz size()
#define gc getchar()
#define pb push_back
/// End.........

/// Size
#define mx7 20000100
#define mx6 1500000
#define mx5 100005
#define mx4 1000100
#define inf 1<<30                                           //infinity value
#define eps 1e-9
#define mx (65540)
#define mod 1000000007
#define pi acos(-1.0)

/// Macros for Graph

#define white 0
#define gray 1
#define black -1
#define nil -2

using namespace std;
/***************/

/// typedef

typedef long long LL;
typedef long L;
typedef unsigned long long ull;
typedef unsigned long ul;
typedef unsigned int ui;
typedef pair<int, int> pii;
typedef vector<int>vi;
typedef vector<long long> vll;
typedef vector<long>vl;
typedef vector<char>vch;
typedef vector<string>vs;
typedef map<int,int>mpii;
typedef map<int,bool>mpbi;
typedef map<char,int>mpci;
typedef map<char,bool>mpbc;
typedef map<string,int>mpsi;
typedef map<long long,long long>mpll;

/// template

template<class T> T gcd(T a, T b ) {return b<=0?a:gcd(b,a%b);}
template<class T> T large(T a, T b ) {return a>b?a:b;}
template<class T> T small(T a, T b ) {return a<b?a:b;}
template<class T> T diffrnce(T a, T b) {return a-b<0?b-a:a-b;}

int main()
{
    string s;

    vi v;

    while(getline(cin,s))
    {
        LL len = s.size();
        v.clear();

        for(LL i=0;i<len;i++)
        {
            if(s[i]=='1')
            {
                //v[i] = 1;
                v.push_back(1);
            }

            else if(s[i]=='0')
            {
                //v[i] = 0;
                v.push_back(0);
            }

            else
            {
                continue;
            }
        }

        //for(int i=0;i<v.size();i++)cout << v[i] << " ";
        int vlen=v.size();

        if(v[0]!=v[1] and v[0]!=v[2])
        {
            pf("A\n");
        }

        else if(v[1]!=v[0] and v[1]!=v[2])
        {
            pf("B\n");
        }

        else if(v[2]!=v[0] and v[2]!=v[1])
        {
            pf("C\n");
        }

        else
        {
            pf("*\n");
        }
    }

    return 0;
}