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

char* _strcat(char *a, char *b) {

  int a_length = strlen(a), b_length = strlen(b);

  char *s = (char *)malloc((a_length + b_length+ 1) * sizeof(char));

  memcpy(s, a, a_length * sizeof(char));
  memcpy(s + a_length, b, b_length * sizeof(char));

  return s;
}