#pragma GCC optimize("Ofast") 
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define mp make_pair                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub upper_bound
#define owo ios_base::sync_with_stdio(0);cin.tie(0);
#define MOD (ll)(998244353)
#define INF (ll)(1e18)
#define debug(...) fprintf(stderr, __VA_ARGS__),fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false);\
debug("%s time : %.4fs\n", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))
typedef long long int ll;
typedef long double ld;
typedef pair<ll,ll> PII;
typedef pair<int,int> pii;
typedef vector<vector<int>> vii;
typedef vector<vector<ll>> VII;
int gcd(int A,int B) {if(!B)return A;return gcd(B,A%B);}
int main()
{
	int n;
	cin>>n;
	ll cnt[60][60];
	for(int i=0;i<60;i++)
		for(int j=0;j<60;j++)cnt[i][j] = 0;
	for(int i=0;i<n;i++){
		ld a;
		cin>>a;
		ll b = (ll)(a*1e9 + 0.5);
		int c2 = 0;
		int c5 = 0;
		while(b%2 == 0){b/=2;c2++;}
		while(b%5 == 0){b/=5;c5++;}
		cnt[c2][c5]++;
	}
	ll ans = 0;
	for(int i=0;i<60;i++){
		for(int j=0;j<60;j++){
			for(int ii=0;ii<60;ii++){
				for(int jj=0;jj<60;jj++){
					if(i+ii >= 18 && j+jj >= 18 && make_pair(i,j) <= make_pair(ii,jj)){
					if(i == ii && j == jj){
					   ans+=cnt[i][j]*(cnt[i][j]-1)/2;	
					}
					else{
						ans+=cnt[i][j]*cnt[ii][jj];
					}
				   }
				}
			}
		}
	}
	 cout<<ans;
 }


Measured memory_bytes: 3696