Language: C++

#include<bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
using namespace std;
typedef long long ll;

int main(){
    ll n;
    cin>>n;
    vector<ll> a(n);
    rep(i,n){
        cin>>a[i];
        if(a[i]==0){
            cout<<0<<endl;
            return 0;
        }
    }
    ll ans=1;
    rep(i,n){
        if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
        else{
            cout<<-1<<endl;
            return 0;
        }
    }
    cout<<ans<<endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:20:29: error: no match for 'operator*' (operand types are 'std::vector<long long int>' and 'll' {aka 'long long int'})
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                            ~^~~~
      |                            | |
      |                            | ll {aka long long int}
      |                            std::vector<long long 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:400:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator*(const complex<_Tp>&, const complex<_Tp>&)'
  400 |     operator*(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:400:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::complex<_Tp>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/complex:409:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator*(const complex<_Tp>&, const _Tp&)'
  409 |     operator*(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:409:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::complex<_Tp>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/complex:418:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator*(const _Tp&, const complex<_Tp>&)'
  418 |     operator*(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:418:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   mismatched types 'const std::complex<_Tp>' and 'll' {aka 'long long int'}
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
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:407:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'll' {aka 'long long int'}
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'll' {aka 'long long int'}
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/valarray:1198:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__multiplies, _Tp>::result_type> std::operator*(const valarray<_Tp>&, const valarray<_Tp>&)'
 1198 | _DEFINE_BINARY_OPERATOR(*, __multiplies)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1198:1: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::valarray<_Tp>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/valarray:1198:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__multiplies, _Tp>::result_type> std::operator*(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1198 | _DEFINE_BINARY_OPERATOR(*, __multiplies)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1198:1: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   'std::vector<long long int>' is not derived from 'const std::valarray<_Tp>'
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~
/usr/include/c++/14/valarray:1198:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__multiplies, _Tp>::result_type> std::operator*(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1198 | _DEFINE_BINARY_OPERATOR(*, __multiplies)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1198:1: note:   template argument deduction/substitution failed:
a.cc:20:30: note:   mismatched types 'const std::valarray<_Tp>' and 'll' {aka 'long long int'}
   20 |         if(a[i]<=1e18/ans&&a*ans<=(ll)1e18) ans*=a[i];
      |                              ^~~