Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
int main(){
	int n;
	cin >> n;
	vector<ull> a(n);
	
	ull ans = 1;
	bool flag = 1;
	for ( ull &i : a ){
		cin >> i;
		if ( i == 0){
			cout << '0' << endl;
			return 0;
		}
		if ( !flag) continue;
		if ( ans > 1000000000000000000 / a ) flag = 0;
		ans *= i;
	}
	
	if ( flag)
		cout << ans << endl;
	else 
		cout << "-1" << endl;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:18:48: error: no match for 'operator/' (operand types are 'long int' and 'std::vector<long long unsigned int>')
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                            ~~~~~~~~~~~~~~~~~~~ ^ ~
      |                            |                     |
      |                            long int              std::vector<long long unsigned int>
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127,
                 from a.cc:1:
/usr/include/c++/14/complex:430:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const complex<_Tp>&)'
  430 |     operator/(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:430:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::complex<_Tp>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/complex:439:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const _Tp&)'
  439 |     operator/(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:439:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::complex<_Tp>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/complex:448:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const _Tp&, const complex<_Tp>&)'
  448 |     operator/(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:448:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   'std::vector<long long unsigned int>' is not derived from 'const std::complex<_Tp>'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   'std::vector<long long unsigned int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   'std::vector<long long unsigned int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::valarray<_Tp>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   mismatched types 'const std::valarray<_Tp>' and 'long int'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:18:50: note:   'std::vector<long long unsigned int>' is not derived from 'const std::valarray<_Tp>'
   18 |                 if ( ans > 1000000000000000000 / a ) flag = 0;
      |                                                  ^