#include <stdio.h>
int main(int argc, char** argv) 
{
    freopen("fact.in", "r", stdin);
    long P;
    scanf("%ld", &P);
    fclose(stdin);
    long N=-1;
    int c=0, i, j;
    for(i=2;c<P;i++) {j=i;
                      while (j%5==0) {c++;j=j/5;}
                     }
    freopen("fact.out", "w", stdout);
    printf("%ld", i-1); 
    fclose(stdout);
    return 0;
}