#include<iostream>
#include<string>
#include<cmath>
using namespace std;
typedef long long ll;
int day[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int year(int year_){
	if(year_%400==0||year_%4==0&&year_%100!=0) return 1;
	else return 0;
}
int month(int month_){
	int sum=0;
	if(year(month_)==1) sum+=1; 
	for(int i=1;i<=10;i++) sum+=day[i];
	sum+=11;
	return sum;
}
int main(){
	int x,y,cnt=0;
	cin>>x>>y;
	for(int i=x;i<=y;i++){
		ll sum=0;
		for(int j=1900;j<=i;j++){
			if(year(j)==1) sum+=366;
			else sum+=365;
		}
		if(month(i)%7==sum%7) cnt++;
		else if(month(i)%7==sum%7-1) cnt++;
		else if(sum%7==0&&month(i)%7==6) cnt++;
	}
	cout<<cnt;
	return 0;
}

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