Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
#define rep(i,n) for(lint (i)=0;(i)<(n);(i)++)
#define repp(i,m,n) for(lint (i)=(m);(i)<(n);(i)++)
#define repm(i,n) for(lint (i)=(n-1);(i)>=0;(i)--)
#define INF (1ll<<60)
#define all(x) (x).begin(),(x).end()
const lint MOD =1000000007;
const lint MAX = 1000000;
using Graph =vector<vector<lint>>;
typedef pair<lint,lint> P;
 
 
lint fac[MAX], finv[MAX], inv[MAX];
 
void COMinit() 
{
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (lint i = 2; i < MAX; i++)
    {
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
 
long long COM(lint n, lint k)
{
    if (n < k)
        return 0;
    if (n < 0 || k < 0)
        return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
 
lint primary(lint num)
{
    if (num < 2) return 0;
    else if (num == 2) return 1;
    else if (num % 2 == 0) return 0;
 
    double sqrtNum = sqrt(num);
    for (int i = 3; i <= sqrtNum; i += 2)
    {
        if (num % i == 0)
        {
            return 0;
        }
    }
 
    return 1;
}
   long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}
    lint lcm(lint a,lint b){
        return a/__gcd(a,b)*b;
    }
     lint gcd(lint a,lint b){
        return __gcd(a,b);
    } 
    
  int main(){      
      string s;
      lint k,n;
      cin>>s>>k;
       n=s.size();
      pair<char,lint> p[n];
      rep(i,n){
            p[i]=make_pair(s[i],i);
      }
      sort(p,p+n);
      set<string> st;
      rep(i,min(n,5)){
            char f;
            lint x;
            tie(f,x)=p[i];
            string an="";
            repp(j,x,n){
                an+=s[j];
             st.emplace(an);
            }
      }
      lint count=0;
     for(auto x:st){
         count++;
        if(count==k){ cout<<x<<endl;
        return 0;
        }
     }
  }
          
  

Compiler output:
a.cc: In function 'int main()':
a.cc:83:16: error: no matching function for call to 'min(lint&, int)'
   83 |       rep(i,min(n,5)){
      |             ~~~^~~~~
a.cc:4:38: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(lint (i)=0;(i)<(n);(i)++)
      |                                      ^
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:233:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)'
  233 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:233:5: note:   template argument deduction/substitution failed:
a.cc:83:16: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
   83 |       rep(i,min(n,5)){
      |             ~~~^~~~~
a.cc:4:38: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(lint (i)=0;(i)<(n);(i)++)
      |                                      ^
/usr/include/c++/14/bits/stl_algobase.h:281:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)'
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:281:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5686:5: note: candidate: 'template<class _Tp> constexpr _Tp std::min(initializer_list<_Tp>)'
 5686 |     min(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5686:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5696:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::min(initializer_list<_Tp>, _Compare)'
 5696 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5696:5: note:   template argument deduction/substitution failed:
a.cc:83:16: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   83 |       rep(i,min(n,5)){
      |             ~~~^~~~~
a.cc:4:38: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(lint (i)=0;(i)<(n);(i)++)
      |                                      ^