#include <stdio.h>
#include <stdlib.h>

int main()
{   int p;
    FILE* f = fopen("fact.in", "r");
    FILE* g = fopen("fact.out", "w");
    fscanf(f, "%d", &p);
    int start = 5;
    int nrZeros = 1;
    int add;
    int copy;
    while (nrZeros < p)
    {
        start += 5;
        copy = start;
        add = 0;
        while (copy % 5 == 0)
        {
            copy /= 5;
            add += 1;
        }
        nrZeros += add;
    }
    fprintf(g, "%d", start);
    return 0;
}