Dirichlet's Theorem on Arithmetic Progressions

 1 #include<stdio.h>
 2 #include<math.h>
 3 int is_prime(int n)
 4 {
 5     int i,m;
 6     if (n==1)
 7         return 0;
 8     m = sqrt(n);
 9     for (i = 2; i <= m; i ++)
10     {
11         if (n%i==0)
12             return 0;
13     }
14     return 1;
15 }
16 int main()
17 {
18     int a,d,n,i;
19     while(~scanf("%d%d%d",&a,&d,&n))
20     {
21         int cnt = 0;
22         if (a==0&&d==0&&n==0)
23             break;
24         for (i = a;; i =i+d)
25         {
26             if(is_prime(i))
27                 cnt++;
28             if(cnt==n)
29                 break;
30         }
31         printf("%d
",i);
32     }
33     return 0;
34 }
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