#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
 
  if(argc != 4) {
    return -1;
  }
  int a1 = atoi(argv[1]);
  int q = atoi(argv[2]);
  int n = atoi(argv[3]);
  printf("a1=%d, n=%d,q=%d\n", a1, n, q);
  int i=0;
  int sum = 0;
  int a = a1;
  while (i < n) {
    sum += a;
    a *= q;
    i++;
  }
  printf("sum=%d\n", sum);
  return 0;
}