#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <functional>
#include <string>
#include <cstring>
#include <cmath>
#include <map>
#include <set>
#include <stack>
#define NMAX 200005
#define MOD 666013
#define INF 0x3f3f3f3f
#define pb push_back

using namespace std;

typedef pair<long long, char> pii;

//ifstream fin("zlego.in");
//ofstream fout("zlego.out");

int sum[10];
int v[10]={0,8,8,6,6,4,4,2,2,0};

int main() {
	long long a,b,suma,sumb;

	sum[1]=sum[2]=1;
	sum[3]=sum[4]=4;
	sum[5]=sum[6]=9;
	sum[7]=sum[8]=16;
	sum[9]=25;


	cin>>a>>b;
	--a;

	suma=a/10*25LL;
	sumb=b/10*25LL;

	suma+=sum[a%10];
	sumb+=sum[b%10];

	suma+=5*((a/10)*(a/10+1)/2) - (a/10!=0)?v[a%10]:0;
	sumb+=5*((b/10)*(b/10+1)/2) - (b/10!=0)?v[b%10]:0;

	cout<<sumb-suma;

	return 0;
}