#include <stdint.h>
#include <assert.h>

int is_it_friday(uint32_t input)
{
        uint32_t SECS_DAY=24*60*60;
        uint32_t dayno = input / SECS_DAY;
        uint32_t wday = (dayno + 4) % 7;
        if (wday==5)
                return 1; // friday
        else
                return 0;
};

void check(uint64_t input)
{
        assert (is_it_friday(input)==0);
};