#include <iostream> using namespace std; int main(){ int n; cin>>n; int c0=0,c1=0,c2=0; for(int i=0;i<n;i++) { int a;cin>>a; int r=a % 3; if(r==0){ c0++; }else if(r==1){ c1++; }else{ c2++; } }int ans=c0; while(c1>0&&c2>0){ c1--; c2--; ans++; }while(c1>=3){ c1-=3; ans++; }while(c2>=3){ c2-=3; ans++; }cout<<ans<<endl; return 0; }