#include using namespace std; #define ALL(x) x.begin(),x.end() #define rep(i,n) for(int i=0;i<(n);i++) #define debug(v) cout<<#v<<":";for(auto x:v){cout<bool chmax(T &a,const T &b){if(abool chmin(T &a,const T &b){if(b ostream &operator<<(ostream &os,const pair&p){ os< ostream &operator<<(ostream &os,const vector&v){ for(int i=0;i<(int)v.size();i++) os<>a>>b; int ans=0; for(int i=a;i<=b;i++)if((a+b+i)%3==0)ans++; cout<