Language: C++

/*input
2
RRSRR
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<long long, null_type, less_equal<long long>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
#pragma GCC optimize("unroll-loops,no-stack-protector")
//order_of_key #of elements less than x
// find_by_order kth element
typedef long long int ll;
#define ld double
#define pii pair<ll,ll>
#define f first
#define s second
#define pb push_back
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<=n;i++)
#define FILL(n,x) memset(n,x,sizeof(n))
#define ALL(_a) _a.begin(),_a.end()
#define sz(x) (int)x.size()
const ll maxn=1e6+5;
const ll maxlg=__lg(maxn)+2;
const ll INF64=4e18;
const int INF=0x3f3f3f3f;
const ll MOD=1e9+7;
const ld PI=acos(-1);
const ld eps=1e-9;
#define lowb(x) x&(-x)
#define MNTO(x,y) x=min(x,(__typeof__(x))y)
#define MXTO(x,y) x=max(x,(__typeof__(x))y)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
#define MP make_pair
ll mult(ll a,ll b){
    ll res=0LL;
    while(b){
        if(b&1) res=(res+a)%MOD;
        a=(a+a)%MOD;
        b>>=1;
    }
    return res%MOD;
}
ll mypow(ll a,ll b){
    ll res=1LL;
    while(b){
        if(b&1) res=res*a%MOD;
        a=a*a%MOD;
        b>>=1;
    }
    return res;
}
int query(string s){
    cout<<s<<endl;
    int x;
    cin>>x;
    return x;
}
bool cmp(string a,string b){
    return sz(a)>sz(b);
}
int main(){
    ios::sync_with_stdio(false),cin.tie(0);
    string alpha="";
    REP(i,26){
        alpha+=('a'+i);
    }
    REP(i,26) alpha+=('A'+i);
    REP(i,10) alpha+=('0'+i);
    vector<string> cur;
    int len=0;
    REP(i,62){
        string z="";
        REP(i,128) z+=alpha[i];
        int cnt=128-query(z);
        string tmp="";
        REP(i,cnt) tmp+=alpha[i];
        cur.pb(tmp);
        len+=cnt;
    }
    while(sz(tmp)>1){
        string a=tmp.back(),b=tmp[sz(tmp)-2];
        tmp.pop_back(),tmp.pop_back();
        int i1=0,i2=0;
        string s="";
        while(i1<sz(a) and i2<sz(b)){
            s+=a[i1++];
            if(query(s)!=len-sz(s)){
                --i1;
                s.pop_back();
                s+=b[i2++];
            }
        }
        while(i1<sz(a)) s+=a[i1];
        while(i2<sz(b)) s+=b[i2];
        cur.pb(s);
        sort(ALL(cur));
    }
    cout<<"! "<<tmp[0];
}

Compiler output:
a.cc: In function 'int main()':
a.cc:84:14: error: 'tmp' was not declared in this scope; did you mean 'tm'?
   84 |     while(sz(tmp)>1){
      |              ^~~
a.cc:24:20: note: in definition of macro 'sz'
   24 | #define sz(x) (int)x.size()
      |                    ^
a.cc:89:34: error: 'b' was not declared in this scope
   89 |         while(i1<sz(a) and i2<sz(b)){
      |                                  ^
a.cc:24:20: note: in definition of macro 'sz'
   24 | #define sz(x) (int)x.size()
      |                    ^
a.cc:98:21: error: 'b' was not declared in this scope
   98 |         while(i2<sz(b)) s+=b[i2];
      |                     ^
a.cc:24:20: note: in definition of macro 'sz'
   24 | #define sz(x) (int)x.size()
      |                    ^
a.cc:102:17: error: 'tmp' was not declared in this scope; did you mean 'tm'?
  102 |     cout<<"! "<<tmp[0];
      |                 ^~~
      |                 tm