#include<cstdlib>

#include<cstdio>

using namespace std;

int main()

{

int i,j,n,m,t,x,f=0;

scanf("%d%d",&n,&m);

for(i=n;i<=m;i++)

{ t=i;

while(t!=0)

{

x=t%10;

if(x==2)

f++;

t=t/10;

}

}

printf("%d",f);

system("pause");

return 0;

}