// Problema factorial

#include <stdio.h>

int main()
{
    long p;
    freopen( "fact.in", "rt", stdin );
             scanf( "%ld", &p );
    fclose( stdin );
    
    long n, m;
    n = 0;
    while( p )
    {
           n = n+5;           
           m = n;
           while( (m%5==0) && p ) { p--; m /= 5; }
    }
    
    freopen( "fact.out", "wt", stdout );
             printf( "%ld\n", n );
    fclose( stdout );
    return 0;
}