#include <vector>
#include <iostream>     // code by Jerry Coffin, 2014-01-04
#include <time.h>       // from http://stackoverflow.com/a/20917972/849891
 
unsigned long primes = 0;
 
int main() {
    // empirically derived limit to get 1,000,000 primes
    int number = 15485865; 
 
    clock_t start = clock();
    std::vector<bool> sieve(number,false);
    sieve[0] = sieve[1] = true;
 
    for(int i = 2; i<number; i++) {
        if(!sieve[i]) {
            ++primes;
            for (int temp = 2*i; temp<number; temp += i)
                sieve[temp] = true;
        }
    }
    clock_t stop = clock();
 
    std::cout.imbue(std::locale(""));
    std::cout << "Total primes: " << primes << "\n";
    std::cout << "Time: " << double(stop - start) / CLOCKS_PER_SEC << " seconds\n";
    return 0;
}

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