Language: C++

#include <bits/stdc++.h>
using namespace std;

int main(){
    int n;
    cin >> n;

    vector<double> x(n);
    vector<double> y(n);
    for(int i = 0; i < n; i++){
        cin >> x[i] >> y[i];
    }

    double cnt = 0;
    double sum = 0;
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            if(i == j)
                continue;
            double absx = abs(x[i]-x[j],2);
            double absy = abs(y[i]-y[j],2);
            sum += sqrt(absx + absy);
            cnt++;
        }
    }

    double ans = sum / cnt;

    cout << ans << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:20:30: error: no matching function for call to 'abs(__gnu_cxx::__alloc_traits<std::allocator<double>, double>::value_type, int)'
   20 |             double absx = abs(x[i]-x[j],2);
      |                           ~~~^~~~~~~~~~~~~
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166,
                 from a.cc:1:
/usr/include/c++/14/bits/valarray_after.h:445:5: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_UnClos<std::_Abs, std::_ValArray, _Tp>, _Tp> std::abs(const valarray<_Tp>&)'
  445 |     _DEFINE_EXPR_UNARY_FUNCTION(abs, struct std::_Abs)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:445:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/valarray_after.h:445:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_UnClos<std::_Abs, std::_Expr, _Dom>, typename _Dom::value_type> std::abs(const _Expr<_Dom1, typename _Dom1::value_type>&)'
  445 |     _DEFINE_EXPR_UNARY_FUNCTION(abs, struct std::_Abs)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:445:5: note:   candidate expects 1 argument, 2 provided
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/complex:892:5: note: candidate: 'template<class _Tp> _Tp std::abs(const complex<_Tp>&)'
  892 |     abs(const complex<_Tp>& __z) { return __complex_abs(__z.__rep()); }
      |     ^~~
/usr/include/c++/14/complex:892:5: note:   candidate expects 1 argument, 2 provided
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:980:12: note: candidate: 'int abs(int)'
  980 | extern int abs (int __x) __THROW __attribute__ ((__const__)) __wur;
      |            ^~~
/usr/include/stdlib.h:980:12: note:   candidate expects 1 argument, 2 provided
In file included from /usr/include/c++/14/cstdlib:81:
/usr/include/c++/14/bits/std_abs.h:137:3: note: candidate: 'constexpr __float128 std::abs(__float128)'
  137 |   abs(__float128 __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:137:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:85:3: note: candidate: 'constexpr __int128 std::abs(__int128)'
   85 |   abs(__GLIBCXX_TYPE_INT_N_0 __x) { return __x >= 0 ? __x : -__x; }
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:85:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:79:3: note: candidate: 'constexpr long double std::abs(long double)'
   79 |   abs(long double __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:79:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:75:3: note: candidate: 'constexpr float std::abs(float)'
   75 |   abs(float __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:75:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:71:3: note: candidate: 'constexpr double std::abs(double)'
   71 |   abs(double __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:71:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:61:3: note: candidate: 'long long int std::abs(long long int)'
   61 |   abs(long long __x) { return __builtin_llabs (__x); }
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:61:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:56:3: note: candidate: 'long int std::abs(long int)'
   56 |   abs(long __i) { return __builtin_labs(__i); }
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:56:3: note:   candidate expects 1 argument, 2 provided
a.cc:21:30: error: no matching function for call to 'abs(__gnu_cxx::__alloc_traits<std::allocator<double>, double>::value_type, int)'
   21 |             double absy = abs(y[i]-y[j],2);
      |                           ~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:445:5: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_UnClos<std::_Abs, std::_ValArray, _Tp>, _Tp> std::abs(const valarray<_Tp>&)'
  445 |     _DEFINE_EXPR_UNARY_FUNCTION(abs, struct std::_Abs)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:445:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/valarray_after.h:445:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_UnClos<std::_Abs, std::_Expr, _Dom>, typename _Dom::value_type> std::abs(const _Expr<_Dom1, typename _Dom1::value_type>&)'
  445 |     _DEFINE_EXPR_UNARY_FUNCTION(abs, struct std::_Abs)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:445:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/complex:892:5: note: candidate: 'template<class _Tp> _Tp std::abs(const complex<_Tp>&)'
  892 |     abs(const complex<_Tp>& __z) { return __complex_abs(__z.__rep()); }
      |     ^~~
/usr/include/c++/14/complex:892:5: note:   candidate expects 1 argument, 2 provided
/usr/include/stdlib.h:980:12: note: candidate: 'int abs(int)'
  980 | extern int abs (int __x) __THROW __attribute__ ((__const__)) __wur;
      |            ^~~
/usr/include/stdlib.h:980:12: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:137:3: note: candidate: 'constexpr __float128 std::abs(__float128)'
  137 |   abs(__float128 __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:137:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:85:3: note: candidate: 'constexpr __int128 std::abs(__int128)'
   85 |   abs(__GLIBCXX_TYPE_INT_N_0 __x) { return __x >= 0 ? __x : -__x; }
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:85:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:79:3: note: candidate: 'constexpr long double std::abs(long double)'
   79 |   abs(long double __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:79:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:75:3: note: candidate: 'constexpr float std::abs(float)'
   75 |   abs(float __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:75:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:71:3: note: candidate: 'constexpr double std::abs(double)'
   71 |   abs(double __x)
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:71:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:61:3: note: candidate: 'long long int std::abs(long long int)'
   61 |   abs(long long __x) { return __builtin_llabs (__x); }
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:61:3: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/std_abs.h:56:3: note: candidate: 'long int std::abs(long int)'
   56 |   abs(long __i) { return __builtin_labs(__i); }
      |   ^~~
/usr/include/c++/14/bits/std_abs.h:56:3: note:   candidate expects 1 argument, 2 provided