题解

只要分母能被除2和5外的素数整除就是无限不循环小数，所以一直除以2和5

#include<cstdio>
using namespace std;
bool f(int x){
    while(x>1){
        if(x%2==0)x/=2;
        else if(x%5==0)x/=5;
        else return 0;
    }
    return 1;
}
int main(){
    int l,r,ans=0;
    scanf("%d%d",&l,&r);
    for(int i=l;i<=r;i++)
        if(f(i))ans++;
    printf("%d",ans);
    return 0;
}