#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>using namespace std;long long x,ans,sum,cn2,cn1;int n;int main(){ while(scanf("%d",&n)==1) { ans=0; cn2=0; cn1=0; for(int i=1;i<=n;i++) { scanf("%I64d",&x); ans+=x/3; if(x%3==2) cn2++; if(x%3==1) cn1++; } sum=ans; if(ans==0) {printf("0n");continue;} ans+=cn2; if(sum<=cn1) ans+=(sum-1); else { ans+=cn1; ans+=(sum-cn1-1)/2; } printf("%lldn",ans); } return 0;}
