#include <stddef.h>

size_t strcspn(const char *dest, const char *src)
{
	size_t i = 0;
	for (i = 0; dest[i]; i++) {
		for (size_t ii = 0; src[ii]; i++) {
			if (dest[i] == src[ii]) {
				return i;
			}
		}
	}

	return i;
}