Language: C++

#include<bits/stdc++.h>
#define ll long long
#define mp make_pair
#define F first
#define S second
#define db double
#define pb push_back
#define rep(i,a,b)  for(ll i=a;i<=b;i++)
using namespace std;
 
 ll mod=998244353;
 
ll expo(ll base,ll exponent,ll mod){
    ll ans=1;
    while(exponent!=0){
        if(exponent&1) ans=(1LL*ans*base)%mod;
        base=(1LL*base*base)%mod;
        exponent>>=1;
    }
    return ans%mod;
}
 
vector<bool>  prime(90000002,true);
void Sieve() 
{ 
   
    for (int p=2; p*p<=90000001; p++) 
    { 
        // If prime[p] is not changed, then it is a prime 
        if (prime[p] == true) 
        { 
            for (int i=p*p; i<=90000001; i += p) 
                prime[i] = false; 
        } 
    } 
}

const ll M=200006;
ll f[M],inv[M];

void compute(){
    f[0]=1;
    rep(i,1,M-1){
        f[i]=(1LL*i*f[i-1])%mod;
    }
    inv[M-1]=expo(f[M-1],mod-2,mod);
    for(ll i=M-2;i>=0;i--){
        inv[i]=(1LL*(i+1)*inv[i+1])%mod;
    }
}
ll C(ll n,ll r){
    return (1LL*((1LL*f[n]*inv[r])%mod)*inv[n-r])%mod;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    // compute();
    // Sieve();
    ll tests=1;
    // cin>>tests;
    while(tests--)
    {
      ll i,j,n,zero=0;
      cin>>n;
      vector<ll>a(n);
      rep(i,0,n-1) 
      {
        cin>>a[i];
        if(a[i]==0) zero++;
      }
      if(zero>0) {cout<<0;return 0;}
      ll cnt=to_string(a[0]).length(),ans=1;
      rep(i,1,n-1)
      {
        cnt+=to_string(a[i]).length()-1;
      }
      if(cnt>19) {cout<<-1; return 0;}
      // ll zero=0;
      rep(i,0,n-1)
      {
        // if(a[i]==0) {zero++;break;}
        // ans*=a[i];
        ll prev=ans;
         cnt=to_string(ans).length() + to_string(a[i])-1;
        ans*=a[i];
        if(ans>1000000000000000000 || ans<prev || cnt>19) {cout<<-1; return 0;}
      }
      // if(zero>0) cout<<0;
      // else
      cout<<ans;
    }
    return 0;
   }

Compiler output:
a.cc: In function 'int main()':
a.cc:86:38: error: no match for 'operator+' (operand types are 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |              ~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~
      |                                   |             |
      |                                   |             std::string {aka std::__cxx11::basic_string<char>}
      |                                   std::__cxx11::basic_string<char>::size_type {aka long unsigned int}
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 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_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'const _CharT*' and 'long unsigned int'
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   deduced conflicting types for parameter '_CharT' ('long unsigned int' and 'char')
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   mismatched types 'const _CharT*' and 'long unsigned int'
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3726:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3726 |     operator+(_CharT __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note:   template argument deduction/substitution failed:
a.cc:86:54: note:   deduced conflicting types for parameter '_CharT' ('long unsigned int' and 'char')
   86 |          cnt=to_string(ans).length() + to_string(a[i])-1;
      |                                                      ^
/usr/include/c++/14/bits/basic_string.h:3733:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*)'
 3733 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note: