#include <stdio.h>

int concat(int * a, int an, int * b, int bn, int * c) {
  if (!a || !b || !c)
    return -1;
  int i, j = 0;
  for (i = 0; i < an; i++) {
    c[j] = a[i];
    j++;
  }
  for (i = 0; i < bn; i++) {
    c[j] = b[i];
    j++;
  }
  return 0;
}

int main() {
  int a[] = {0, 1, 2};
  int b[] = {3, 4, 5, 6};
  int c[7];
  concat(a, 3, b, 4, c);
  int i;
  for (i = 0; i < 7; ++i)
    printf("%d ", c[i]);
  printf("\n");
  return 0;
}