UVa 11408

#include<bits/stdc++.h>
using namespace std;

// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
// #pragma GCC optimize("unroll-loops")

typedef unsigned long long ull;
typedef long long          ll;
typedef long double        lld;
typedef vector<int>        vi;
typedef vector<ll>         vll;
typedef vector<vi>         vvi;
typedef pair<int,int >     pii;
typedef pair<ll,ll >       pll;
typedef vector< pii >      vpii;
typedef vector< pll >      vpll;
typedef set<int>           sti;

#define sc                 scanf
#define pf                 printf
#define sci(n)             scanf("%d",&n)
#define scii(n,m)          scanf("%d %d",&n,&m)
#define scl(n)             scanf("%lld",&n)
#define scd(n)             scanf("%lf",&n)
#define scs(s)             scanf("%s",s)
#define pfi(n)             printf("%d",n)
#define pfl(n)             printf("%lld",n)
#define pff(n)             cout<<n
#define spc                printf(" ")
#define line               printf("\n")
#define loop(i,x,y)        for(int i=int(x); i<=int(y); i++)
#define rloop(i,y,x)       for(int i=int(y); i>=int(x); i--)
#define cspf(i)            printf("Case %d: ", i)
#define vout(v)            for(int w=0;w<v.size();w++){if(w) cout<<' '; cout<<v[w];}
#define clr(a,x)           memset(a,x,sizeof(a))
#define tp(v,j)            get<j>(v)
#define pb                 push_back
#define mp                 make_pair
#define mt                 make_tuple
#define ff                 first
#define ss                 second
#define all(v)             v.begin(),v.end()
#define rall(v)            v.rbegin(),v.rend()
#define read()             freopen("input.txt", "r", stdin)
#define write()            freopen("output.txt", "w", stdout)
#define fastIO()           ios_base::sync_with_stdio(false); cin.tie(NULL);
/// Constants
#define eps                1e-9
#define PI                 acos(-1.0)  // 3.1415926535897932
#define MAX                (ll)2147483647
#define MAXn               5000015

int GCD(int a, int b) { return b == 0 ? a : GCD(b , a % b); }
ll LCM(ll a, ll b) { return a * (b/GCD(a, b)); }

int pre[MAXn];
int val[MAXn];
int cnt[MAXn];

void seive()
{
    for(int i=4;i<MAXn;i+=2) pre[i]=2;
    for(int i=3;i<=MAXn/i;i+=2){
        if(pre[i]) continue;
        for(int j=i*i;j<MAXn;j+=(2*i)){
            if(!pre[j]) pre[j]=i;
        }
    }
    for(int i=0;i<MAXn;i++){
        if(!pre[i]) pre[i]=i;
    }
    for(int i=2;i<MAXn;i++){
        int x = pre[i];
        int y=i;
        int z=0;
        while(x>1 && y%x==0){
            while(y%x==0) y/=x;
            z+=x;
            x = pre[y];
        }
        val[i]=z;
    }
    for(int i=2;i<MAXn-10;i++){
        if(pre[val[i]]==val[i]) cnt[i]=cnt[i-1]+1;
        else cnt[i]=cnt[i-1];
    }
}

int main()
{
    #ifdef VAMP
        clock_t tStart = clock();
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif

    seive();
    while(1){
        int a,b;
        sci(a);
        if(!a) break;
        sci(b);
        pfi(cnt[b]-cnt[a-1]);line;
    }


    #ifdef VAMP
        fprintf(stderr, "\n>> Runtime: %.10fs\n", (double) (clock() - tStart) / CLOCKS_PER_SEC);
    #endif

    return 0;
}