Basic decimal to binary in C

hexbin.c

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

int main() {
	int decimal;
	int *sequence = NULL;
	int size = 0;

	printf("Enter a decimal number: ");
	scanf("%d", &decimal);

	if(decimal < 0) {
		printf("Invalid input\n");
		return 0;
	} else if(decimal == 0) {
		printf("0\n");
		return 0;
	}

	while(decimal > 0) {
		sequence = (int *)realloc(sequence, sizeof(int) * (size + 1));
		sequence[size] = decimal % 2;
		decimal /= 2;
		size++;
	}

	for(int i = size - 1; i >= 0; i--) {
		printf("%d", sequence[i]);
	}

	free(sequence);

	printf("\n");

	return 0;
}