#include <stdio.h>

long power_mod(long base, long exp, long mod) {
  long result = 1;
  base = base % mod;
  while (exp > 0) {
    if (exp % 2 == 1) result = (result * base) % mod;
    base = (base * base) % mod;
    exp = exp / 2;
  }
  return result;
}

int main() {
  long p = 23, g = 5;
  long a = 6, b = 15;
  long A = power_mod(g, a, p);
  long B = power_mod(g, b, p);
  long secretA = power_mod(B, a, p);
  long secretB = power_mod(A, b, p);
  printf("Alice sends A = %ld\n", A);
  printf("Bob sends   B = %ld\n", B);
  printf("Alice secret = %ld\n", secretA);
  printf("Bob secret   = %ld\n", secretB);
  return 0;
}