Language: C++

#include <bits/stdc++.h>
#define ll long long
#define rep(X,N) for(int X = 0; X < N; X++)

using namespace std;

int main(){

    string s;
    ll k;

    cin >> s;
    cin >> k;

    int ans = 1;

    for(int i = 0; i < min(s.size(),k); i++){

        if(s[i] != '1'){
            ans = atoi(s[i]);
            break;
        }

    }

    cout << ans << endl;

    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:27: error: no matching function for call to 'min(std::__cxx11::basic_string<char>::size_type, long long int&)'
   17 |     for(int i = 0; i < min(s.size(),k); 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:17:27: note:   deduced conflicting types for parameter 'const _Tp' ('long unsigned int' and 'long long int')
   17 |     for(int i = 0; i < min(s.size(),k); 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:17:27: note:   mismatched types 'std::initializer_list<_Tp>' and 'long unsigned int'
   17 |     for(int i = 0; i < min(s.size(),k); i++){
      |                        ~~~^~~~~~~~~~~~
a.cc:20:23: error: invalid conversion from '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} to 'const char*' [-fpermissive]
   20 |             ans = atoi(s[i]);
      |                   ~~~~^~~~~~
      |                       |
      |                       __gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type {aka char}
In file included from /usr/include/c++/14/cstdlib:79,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:42:
/usr/include/stdlib.h:105:30: note:   initializing argument 1 of 'int atoi(const char*)'
  105 | extern int atoi (const char *__nptr)
      |                  ~~~~~~~~~~~~^~~~~~