#include <iostream>
#include <cstdio>
using namespace std;
FILE*fin=fopen("fact.in","r");
FILE*fout=fopen("fact.out","w");
int main()
{
    int n , p , k = 0 , x , i ;
    fscanf( fin , "%d" , &p );
    for ( i = 1 ; i <= p * 5  ; ++i )
    {
        if ( i % 5 == 0 )
        {
            x = i ;
            if ( ( i / 5 ) % 5 == 0 )
            {
                while ( x % 5 == 0 )
                {
                    ++k ;
                    x /= 5 ;
                }
            }
            else ++k ;
        if ( k >= p ) break ;
        }
    }
    fprintf( fout , "%d" , i) ;
    return 0;
}