Language: C++

#include<iostream>
#include<string>
#include<algorithm>
#define int long long
using namespace std;
int a[200000];
signed main(){
	int n;
	string s;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>s;
		int dot=100;
		for(int j=0;j<s.size();j++)
			if(s[j]=='.')
				dot=j;
		if(dot!=100)
			s.erase(s.begin()+dot);
		a[i]=stoll(s)*(int)round(pow(10,9-max(0ll,s.size()-dot)));
	}
	int dd[19][19]={};
	for(int i=0;i<n;i++){
		int a2=a[i],a5=a[i];
		int div2=0,div5=0;
		while(a2%2==0){
			a2/=2;
			div2++;
		}
		while(a5%5==0){
			a5/=5;
			div5++;
		}
		dd[min(18ll,div2)][min(18ll,div5)]++;
	}
	int ans=0;
	for(int i=0;i<=18;i++)
		for(int j=0;j<=18;j++)
			for(int k=18-i;k<=18;k++)
				for(int l=18-j;l<=18;l++)
					if(i==k&&j==l)
						ans+=dd[i][j]*(dd[i][j]-1);
					else
						ans+=dd[i][j]*dd[k][l];
	cout<<ans/2<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:19:54: error: no matching function for call to 'max(long long int, long long unsigned int)'
   19 |                 a[i]=stoll(s)*(int)round(pow(10,9-max(0ll,s.size()-dot)));
      |                                                   ~~~^~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:19:54: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'long long unsigned int')
   19 |                 a[i]=stoll(s)*(int)round(pow(10,9-max(0ll,s.size()-dot)));
      |                                                   ~~~^~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:19:54: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   19 |                 a[i]=stoll(s)*(int)round(pow(10,9-max(0ll,s.size()-dot)));
      |                                                   ~~~^~~~~~~~~~~~~~~~~~
a.cc:19:42: error: 'pow' was not declared in this scope
   19 |                 a[i]=stoll(s)*(int)round(pow(10,9-max(0ll,s.size()-dot)));
      |                                          ^~~
a.cc:19:36: error: 'round' was not declared in this scope
   19 |                 a[i]=stoll(s)*(int)round(pow(10,9-max(0ll,s.size()-dot)));
      |                                    ^~~~~