POJ3006

 1 #include <iostream>
 2 #include <math.h>
 3 using namespace std;
 4 
 5 int main()
 6 {
 7     int N = 1000000;
 8     bool prime[N+1];
 9     for (int i = 0; i < N; i++)
10     {
11         if (i%2 == 0 && i != 2)
12             prime[i] = false;
13         else
14             prime[i] = true;
15     }
16     prime[1] = false;
17     for (int i = 3; i <= sqrt(N); i += 2)
18     {
19         if (prime[i])
20             for (int j = i+i; j <= N; j += i)
21                 prime[j] = false;
22     }
23 
24     int a, d, n;
25     int seq;
26     int nth;
27     while (cin >> a >> d >> n)
28     {
29         seq = a;
30         nth = 1;
31         if (a == 0 && d == 0 && n == 0)
32             return 0;
33 
34         while (1)
35         {
36             if (prime[seq] && nth == n)
37                 break;
38             if (prime[seq])
39                 nth++;
40             seq += d;
41         }
42         
43         cout << seq << endl;
44     }
45 
46     return 0;
47 }