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

#define N 1024

void reverse(int v[], int n) {
  int i, j, tmp;
  for (i = 0, j = n - 1; i < j; i++, j--) {
    tmp = v[i];
    v[i] = v[j];
    v[j] = tmp;
  }
}

int main() {
  char buff[N];
  int i, n;
  int *va;
  /* input n */
  printf("n = ");
  fgets(buff, N, stdin);
  n = atoi(buff);
  va = malloc(sizeof(int) * n);
  if (va) {
    for (i = 0; i < n; i++) {
      printf("va[%d] = ", i);
      fgets(buff, N, stdin);
      va[i] = atoi(buff);
    }
    printf("before:\n");
    for (i = 0; i < n; i++)
      printf("va[%d] = %d\n", i, va[i]);
    reverse(va, n);
    printf("after:\n");
    for (i = 0; i < n; i++)
      printf("va[%d] = %d\n", i, va[i]);
    free(va);
  }
  return 0;
}
/* end */

n = before:
after: