#include<iostream> using namespace std; int main(){ int num,s1 = 0,s2 = 0,s3 = 0,ans; cin>>num; int group[num]; for(int i = 0; i < num; i++){ cin>>group[i]; if(group[i] % 3 == 0){ s3++; }else if(group[i] % 3 == 1){ s1++; }else{ s2++; } } ans = s3 + min(s1,s2); if(s1 > s2){ ans += (s1 - s2) / 3; }else{ ans += (s2 - s1) / 3; } cout<<ans; }