Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var scanner = bufio.NewScanner(os.Stdin)

const (
	MAX  = 1000000
	SQRT = 1000
)

func main() {
	comp := make([]int, MAX+2)
	sieve := func() {
		for i := 3; i < SQRT; i += 2 {
			if comp[i] == 0 {
				for j := i * i; j < MAX; j += i {
					comp[j] = 1
				}
			}
		}
	}
	sieve()
	tbl := make([]int, MAX+2)
	tbl[2] = 1
	k := 1
	for i := 3; i < MAX; i += 2 {
		if comp[i] == 0 {
			k++
		}
		tbl[i+1], tbl[i] = k, k
	}
	for scanner.Scan() {
		n, _ := strconv.Atoi(scanner.Text())
		if n == 0 {
			break
		}
		ans := 0
		for i := 0; i < n; i++ {
			scanner.Scan()
			buf := strings.Split(scanner.Text(), " ")
			p, _ := strconv.Atoi(buf[0])
			m, _ := strconv.Atoi(buf[1])
			a, b := p-m, p+m
			if a < 2 {
				a = 2
			}
			if b > MAX {
				b = MAX
			}
			ans += tbl[b] - tbl[a-1] - 1
		}
		if ans < 0 {
			ans = 0
		}
		fmt.Println(ans)
	}
}

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

#define pb(n) push_back(n)
#define fi first
#define se second
#define all(r) (r).begin(),(r).end()
#define gsort(st,en) sort((st),(en),greater<int>())
#define vmax(ary) *max_element(all(ary))
#define vmin(ary) *min_element(all(ary))
#define debug(x) cout<<#x<<": "<<x<<endl
#define fcout(n) cout<<fixed<<setprecision((n))
#define scout(n) cout<<setw(n)
#define vary(type,name,size,init) vector< type> name(size,init)

#define rep(i,n) for(int i = 0; i < (int)(n);++i)
#define REP(i,a,b) for(int i = (a);i < (int)(b);++i)
#define repi(it,array) for(auto it = array.begin(),end = array.end(); it != end;++it)
#define repa(n,array) for(auto &n :(array))

using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
using dict = map<string,int>;
using pii = pair<int,int> ;

constexpr int imax = ((1<<30)-1)*2+1 ;
constexpr int inf = 100000000;
constexpr double PI = acos(-1.0) ;
double eps = 1e-10 ;
const int dy[] = {-1,0,1,0};
const int dx[] = {0,-1,0,1};

inline bool value(int x,int y,int w,int h){
  return (x >= 0 && x < w && y >= 0 && y < h);
}

template<typename T>
void Unique(vector<T> &v){
  sort(all(v));
  v.erase(unique(all(v)),v.end());
}

template<typename T>
T ston(string& str, T n){
  istringstream sin(str) ;
  T num ;
  sin >> num ;
  return num ;
}

void Ans(bool f){
  if(f) cout << "YES"<<endl;
  else cout << "NO"<<endl;
}

const int PrimeMax = 1000001;
int is_prime[PrimeMax];
void Eratosthenes(int N){
  for(int i = 0; i < N; i++){
    is_prime[i] = 1;
  }
  is_prime[0] = 0;
  is_prime[1] = 0;
  for(int i = 2; i*i < N ; i++){
    if(is_prime[i]){
      for(int j = 0; i * (j + 2) < N; j++){
        is_prime[i *(j + 2)] = 0;
      }
    }
  }
  REP(i,1,N){
    is_prime[i] += is_prime[i-1];
  }
}
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n;
  Eratosthenes(PrimeMax);
  debug(is_prime[5]);
  while(cin>>n&&n){
    rep(i,n){
      ll p,m,ans = 0;
      ll f,s;
      cin >> p>>m;
      if(p - m >= 0){
        s = 0;
      }
      else{
        s = p -m;
      }
      f = (p+m > PrimeMax) ? PrimeMax:p+m;
      if(is_prime[s]- is_prime[f] == 0){
        ans += 1;
      }
      else{
        ans -= (is_prime[s]-is_prime[f] -1);
      }
      cout << ans << endl;
    }
  }
  return 0;
}

C++: #include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cassert>

using namespace std;

#define FOR(i,k,n) for(int i=(k); i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

template<class T> void debug(T begin, T end){ for(T i = begin; i != end; ++i) cerr<<*i<<" "; cerr<<endl; }
inline bool valid(int x, int y, int W, int H){ return (x >= 0 && y >= 0 && x < W && y < H); }

typedef long long ll;
const int INF = 100000000;
const double EPS = 1e-8;
const int MOD = 1000000007;
int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};

int main(){
  const int MAXP = 999983;
  vector<bool> is_prime(MAXP + 1, true);
  is_prime[0] = is_prime[1] = false;
  for(int i = 2; i <= MAXP; i++)if(is_prime[i]){
    if((ll)i * i <= MAXP){
      for(int j = i * i; j <= MAXP; j += i){
        is_prime[j] = false;
      }
    }
  }
  vector<int> acc(MAXP + 1, 0);
  for(int i = 1; i <= MAXP; i++){
    acc[i] = acc[i - 1] + (is_prime[i] ? 1 : 0);
  }
  int N;
  while(cin >> N && N != 0){
    int ans = 0;
    REP(i, N){
      int p, m; cin >> p >> m;
      int left = max(p - m, 1);
      int right = min(p + m, MAXP);
      int cnt = acc[right] - acc[left - 1];
      ans += cnt - 1;
    }
    if(ans < 0) ans = 0;
    cout << ans << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<cmath>
using namespace std;


#define MAX 999985
//素数配列
int h_sosu[MAX] = {0};
//素数flag
bool h_flag_sosu[MAX] = {false};

//----- 列挙関数 -----//
void f_sosu();


int main(void)
{
	//素数を列挙
	f_sosu();

	//入力変数
	int n = 0;

	while (true)
	{
		cin >> n;
		if (n == 0)	{	return 0;	}

		//答え変数(王が1払ってくれる)
		int ans = 0;
		//当たりくじ
		int atari = 0;
		//組
		int kumi = 0;

		//入力
		for (int i = 0; i < n; i++)
		{
			cin >> atari >> kumi;
			//ループ変数
			int j = atari - kumi;
			//終了
			int end = atari + kumi;
			//1は政府が支払う
			bool flag_in = false;

			//負数はいらない
			if (j < 0)	{	j = 0;	}
			//値が大きすぎるなら
			if (end >= MAX)	{end = MAX;	}
			while (j <= end)
			{
				//flagがtrueなら足す
				if (h_flag_sosu[j] == true)
				{
					ans++;
					flag_in = true;
				}
				j++;
			}
			//1回でも入れば
			//if (flag_in == true)
			//{
				ans--;
			//}
		}

		cout << ans << endl;
	}

	return 0;
}



//*****----- 素数列挙(エラトステネスのふるい) -----*****//

void f_sosu()
{
	//2 , 3は加えておく
	register int count = 2;
	h_sosu[0] = 2 , h_sosu[1] = 3;
	h_flag_sosu[2] = true;
	h_flag_sosu[3] = true;
	//終了の値
	register int end = 0;
	//素数flag
	register bool flag_sosu = false;

	for (int i = 5; i < MAX; i += 2)
	{
		//flag初期化
		flag_sosu = true;
		//平方根までで良い
		end = sqrt((double)i);
		//カウント変数まで回す
		for (int j = 0; j < count; j++)
		{
			if (i % h_sosu[j] == 0)
			{
				flag_sosu = false;
				break;
			}
			if (h_sosu[j] > end)	{	break;	}
		}
		//素数なら
		if (flag_sosu == true)
		{
			h_sosu[count++] = i;
			h_flag_sosu[i] = true;
		}
	}
}

C++: #include <iostream>
#include <string.h>
#include <vector>
#include <algorithm>
using namespace std;
#define LIM 1000000
 
bool is_prime[LIM+10];
 
int main(){
    memset(is_prime, true, sizeof(is_prime));
    is_prime[0] = is_prime[1] = false;
 
    for(int p=2;p*p<=LIM;p++)if(is_prime[p]){
        for(int k=p*p;k<=LIM;k+=p)is_prime[k] = false;
    }
 
    vector<int> primes;
    for(int i=2;i<=LIM;i++)if(is_prime[i])primes.push_back(i);
 
    int n;
    while(cin >> n && n){
        int pay = 0;
        for(int i=0;i<n;i++){
            int p, m;
            cin >> p >> m;
 
            pay += upper_bound(primes.begin(), primes.end(), p + m) - lower_bound(primes.begin(), primes.end(), p - m) -  1;
        }
 
        cout << pay << endl;
    }
    return 0;
}

C++: #include<iostream>
#include <algorithm>
#include<functional>//greaterの使用
using namespace std;
#define MAX_LIST 999983+100
#define MP 999983

int main(){
	bool prime[MAX_LIST];
	for(int i=0;i<MAX_LIST;i++){
		prime[i]=1;
	}
	prime[0]=prime[1]=0;
	for(int i=0;i*i<MAX_LIST;i++){
		if(prime[i]==1){
			for(int j=i*2;j<MAX_LIST;j=j+i){
				prime[j]=0;
			}
		}
	}
	for(int i=MP+1;i<MAX_LIST;i++){
		prime[i]=0;
	}
	
	int prime_num[MAX_LIST];
	prime_num[0]=1;
	for(int i=1;i<MP;i++){
		prime_num[i]=prime_num[i-1]+prime[i];
	}
	
	
	int pair_num;
	while(cin>>pair_num,pair_num){
		int ans=0;
		
		for(;pair_num--;){
			int p,m;
			int x;
			cin>>p;
			cin>>m;
			
			if(p+m>MP){
				x=prime_num[MP]-prime_num[p-m];
			}else{
				x=prime_num[p+m]-prime_num[p-m];
			}
			
			if(x<0){
				ans--;
			}else{
				x--;
				ans=ans+x;
			}
		}
		cout<<ans<<endl;
	}
	return 0;
}