#include <iostream> using namespace std; long long n; long long a[100005]; int cnt1,cnt2,cnt3; int main(){ cin>>n; for(int i=1;i<=n;i++){ cin>>a[i]; } for(int i=1;i<=n;i++){ if(a[i]%3==0)cnt1++; else if(a[i]%3==1)cnt2++; else cnt3++; } if(cnt2>cnt3){ cnt2-=cnt3; cnt2/=3; }else{ cnt3-=cnt2; cnt3/=3; } cout<<cnt1+cnt2+cnt3; return 0; }