#include<bits/stdc++.h> using namespace std; int main(){ int a[100001],n,s=0,ss=0,sss=0; cin>>n; for(int i=0;i<n;i++){ cin>>a[i]; if(a[i]%3==0){ s++; }else if(a[i]%3==1){ ss++; }else{ sss++; } } while(ss>0&&sss>0){ ss--; sss--; s++; } while(ss>2){ ss-=3; s++; } while(sss>2){ sss-=3; s++; } cout<<s; return 0; }