#include<stdio.h>
int main(){
int a,b,c,d=0,i,e;
printf("请输入两个数字,1<=a<=b<=500\n");
scanf("%d%d",&a,&b);
for(i=a;i<=b;i++){
while(1<=c<i){
e= i%c;
if(e!=0){
d++;}
}
}
printf("%d",d);
return 0;
}