简单

#include <iostream>
using namespace std;
int main(){
    int n;
    cin >> n;
    int a = n/3600,b = n%3600/60,c = n%3600%60;
    printf("%02d",a);
    cout << ":";
    printf("%02d",b);
    cout << ":";
    printf("%02d",c);
    return 0;
}

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