#include <stdio.h>
#include <stdlib.h>
#define L 28

int nrz( int n ){
    int nr = 0;
    while ( n >= 5 ){
        nr += n / 5;
        n /= 5;
    }
    return nr;
}

int cautb( int p ) {
    int r = 0, pas = 1 << L;
    while ( pas != 0 ){
        if ( nrz( r + pas ) < p ){
            r += pas;
        }
        pas /= 2;
    }
    r ++;
    if ( nrz(r ) != p ){
        r = -1;
    }
    return r;
}

int main(){
    FILE *fin, *fout;
    fin = fopen( "fact.in", "r" );
    fout = fopen( "fact.out", "w" );
    int p, rez;
    fscanf( fin, "%d", &p );
    rez = cautb(p);
    fprintf( fout, "%d" , rez );
    fclose( fin );
    fclose( fout );
    return 0;
}