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++: 
#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <memory>
#include <string>

#include <algorithm>
#include <complex>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <bitset>

using namespace std;

#ifdef _MSC_VER
#define __typeof__ decltype
#define strtok_r strtok_s
#endif

#define ITER(c)             __typeof__((c).begin())
#define FOREACH(it, c)      for (ITER(c) it=(c).begin(); it != (c).end(); ++it)
#define RITER(c)            __typeof__((c).rbegin())
#define RFOREACH(it, c)     for (RITER(c) it=(c).rbegin(); it != (c).rend(); ++it)
#define REP(i, n)           REPEAT(i, 0, n)
#define RREP(i, n)          RREPEAT(i, 0, n)
#define REPEAT(i, k, n)     for(int i = (k); i < ((k)+(n)); ++i)
#define RREPEAT(i, k, n)    for(int i = (k)+(n)-1; i >= (k); --i)
#define FROMTO(i,f,t)       for(int i = f; i < t; i++)
#define ALL(c)              (c).begin(), (c).end()
#define LLPOW(p1,p2)        ((ll)pow((double)(p1), (int)p2))
#define ESIZEOF(A)          (sizeof(A)/sizeof((A)[0]))
#define CIN_NO_SYNC         do { cin.tie(0); ios_base::sync_with_stdio(false); } while(0)
#define GETSTR(p)           fgets((p), sizeof(p), stdin)
#define CHOMP(p)            do{ char *_q = (p) + strlen(p)-1; if(*_q == '\n' || *_q == '\r') *_q = 0; } while(0)
#define FILL(m,v)           memset(m, v, sizeof(m))
#define mp                  make_pair
#define pb                  push_back
template<class _T> _T MAX(_T p1,_T p2){return (p1>p2)?p1:p2;} 
template<class _T> _T MIN(_T p1,_T p2){return (p1<p2)?p1:p2;} 
template <class _Tv> inline string join(const _Tv &v,string sep=" "){
    ostringstream s;FOREACH(it,v){if(it!=v.begin())s<<sep;s<<*it;};return s.str();
}

typedef long long ll;
typedef unsigned long long ull;
typedef double D;
typedef complex<D> P;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define X real()
#define Y imag()
#define EPS (1e-9)
#define DEQ(p1,p2) (abs((p1)-(p2)) < EPS)

#ifdef _DEBUG
template<class _Tv> inline void _prfe(const char *_n,const _Tv _c,bool _p=false){
    ITER(_c) _it=_c.begin();
    if(_p){cout<<_n<<" = ["<<endl;for(;_it!=_c.end();++_it)cout<<"    "<<*_it<<endl;cout<<"]"<<endl; }
    else{cout<<_n<<" = [ "<<*_it++;for(;_it!=_c.end();++_it)cout<<", "<<*_it;cout<<" ]"<<endl; }
}
ostream &operator<<(ostream &os, const pair<int,int> &p){return(os<<"("<<p.first<<","<<p.second<<")");}
#define pf printf
#define pr(n) do{cout<<#n" = "<<(n)<<endl;}while(0)
#define prfe(n) _prfe(#n, n)
#define prfep(n) _prfe(#n, n, true)
#define dbgchk(n) do{if(n)throw;}while(0)
#else
#define pf(...) /* */
#define pr(...) /* */
#define prfe(...) /* */
#define prfep(...) /* */
#define dbgchk(...) /* */
#endif

const int lim = 1000000;
int prime[lim+10];

int main(){
    for(int i = 2; i <= lim; i++) prime[i] = 1;
    for(int i = 2; i <= lim; i++){
        if(prime[i]){
            for(int j = i*2; j <= lim; j += i){
                prime[j] = 0;
            }
        }
        prime[i] += prime[i-1];
    }

    int n;
    while(cin >> n && n){
        int t = 0, p, m;
        REP(i,n){
            cin >> p >> m;
            int p1 = p-m; if(p1 < 0) p1 = 0;
            int p2 = p+m; if(p2 > lim) p2 = lim;
            t += (prime[p2]-prime[p1-1])-1;
        }
        cout << t << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace std;

#define M 1000000

int m[3] = { 2, 7, 61 }; 

long mod(long a, long d, long n){
	if(a==0 || n==0) return 0;
	if(d==0) return 1 % n;
	
	unsigned long currentMod = a % n;
	unsigned long currentValue = (d%2 == 1) ? currentMod : 1;
	
	for(d>>=1; d>0; d>>=1){
		currentMod = (currentMod * currentMod) % n;
		if(d%2 == 1){
			currentValue = (currentValue * currentMod) % n;
		}
	}
	
	return currentValue;
}

bool isPrime(long x){
	if(x==2){
		return true;
	}
	else if(x%2 == 0){
		return false;
	}
	else if(x != 3 && x%6 != 1 && x%6 != x-1){
		return false;
	}
	else{
		long s = 0;
		long d = x - 1;
		while(d%2 == 0){
			d = d / 2;
			s++;
		}
		
		for(int i=0; i<3; i++){
			long a = m[i];
			if(a%x == 0) continue;
			
			long pow = mod(a, d, x);
			if(pow == 1) continue;
			if(pow == x - 1) continue;
			
			bool con2 = false;
			for(int r=1; r<s; r++){
				pow = mod(pow, 2, x);
				if(pow ==  x - 1){
					con2 = true;
					break;
				}
			}
			
			if(!con2){
				return false;
			}
		}
		
		return true;
	}
}

int main(int argc, char** argv)
{
	char str[128];
	int* prime;
	int i, c, n, pay, size, cen, ran;

	prime = new int[M];

	while(true){
		cin >> str;
		size = atoi(str);
		if(size == 0) break;

		pay = 0;
		for(n=0; n<size; n++){
			cin >> str;
			cen = atoi(str);
			cin >> str;
			ran = atoi(str);
			c = 0;
			for(i=max(2, cen-ran); i<=min(cen+ran, M); i++){
				if(prime[i] != 0 && prime[i] != 1){
					if(isPrime(i)){
						prime[i] = 1;
						c++;
					}
					else{
						prime[i] = 0;
					}
				}
				else{
					if(prime[i]==1){
						c++;
					}
				}
			}

			pay += c - 1;
		}

		cout << max(0, pay) << endl;
	}

	delete prime;
}

C++: #include <iostream>
#include <cmath>
#define MAX 1000000
//78498
using namespace std;

bool prime[MAX+1];

int count(int p, int m){
  int tmp=0;
  int d, u;
  d=p-m;
  if(d<0) d=0;
  u=p+m;
  if(u>MAX) u=MAX;
  for(int i=d;i<=u;i++){
    if(prime[i]) tmp++;
  }
  if(tmp==0){
    return -1;
  }else{
    return tmp-1;
  }
}

void eratos(){
  int n=MAX;
  for(int i=0;i<=n;i++) prime[i]=false;
  for(int i=3;i<=n;i+=2) prime[i]=true;
  prime[2]=true;
  int limit=(int)sqrt((double)n)+1;
  for(int i=3;i<=limit;i+=2){
    if(!prime[i]) continue;
    for(int j=i+i;j<=n;j+=i)
      prime[j]=false;
  }
}

main(){
  int n;
  eratos();
  while(1){
    cin >> n;
    if(n==0) break;
    int ans=0;
    for(int i=0;i<n;i++){
      int p, m;
      cin >> p >> m;
      ans+=count(p, m);
    }
    cout << ans << endl;
  }
  return 0;
}