include

using namespace std;

int sum=0;

void get2(int n)

{

if(n%10==2)

    sum++;

if(n/10>0)

    return get2(n/10);

}

int main()

{

int a,b;

cin>>a>>b;

for(int i=a;i<=b;i++)

    get2(i);

cout<<sum;

}