== 这题需要注意的就是输入的时间是毫秒且范围是10的18次方,因此要定义长整型 ==
#include<bits/stdc++.h>
using namespace std;
int main()
{
long long num;
cin>>num;
long long ss;
int h = 0,m = 0,s = 0;
//将毫秒变成秒
ss = num/1000;
h = (ss/3600)%24;
m = (ss/60)%60;
s = ss%60;
printf("%02d:%02d:%02d",h,m,s);
return 0;
}