This is the SPOJ Problem PRIME1.

PRIME1.cpp

#include<iostream>
using namespace std;
#include<cstdio>
#include<cmath>
#include<cstring>
#include<vector>
typedef long long ll; 

void segseive( ll l, ll r){
    ll limit = sqrt(r), diff = limit+1, arr[diff],i,j, seivearr[1000], start, num, set;
    memset(arr, 0 , sizeof(arr));
    vector<ll> primes;
    vector<ll>::iterator it;
    arr[0] = arr[1] = 1;
    for( i = 0; i <= limit; i++){
        if( !arr[i] ){
            primes.push_back(i);
            for( j = i+i; j<=limit; j+= i){
                arr[j] = 1;
            }
        }
    }

    
    for( i=l; i<=r; i+= 1000){
        start = i;
        memset(seivearr, 0 , sizeof(seivearr));
        for(it = primes.begin(); it != primes.end(); it++){
            num = *it;
            set = num - (start %num);
            if( start%num ==0 && start>num)
                seivearr[0] = 1;
            for( j = set ; j<1000 && start + j<=r; j+= num){
                if( start+j <= num)
                    continue;
                seivearr[j] = 1;
            }
        }
        for( j = 0; j< 1000 && j+start <= r; j++){
            num = j+start;
            if( !seivearr[j] && num != 0 && num != 1)
                printf("%lld\n", start+j);
        }
    }
    cout<<endl;
}

int main(){
    ll l, r;
    int t;
    for( scanf("%d", &t); t; t--){
        scanf("%lld%lld", &l, &r);
        segseive(l,r);
    }
    return 0;
}