#include <cstdio>
using namespace std;
int main()
{
    FILE * iFile;
    FILE * oFile;

    iFile = fopen("fact.in", "r");
    oFile = fopen("fact.out", "w");

    long long int n=1, p, ucif=0, ok=0, count=0, factorial=1, i;

    fscanf(iFile,"%llu", &p);

    while(ok == 0)
    {
        factorial = 1;
        for(i=1;i<=n;i++)
        {
            factorial = factorial * i;
        }
        while(ucif == 0)
        {
            ucif = factorial % 10;
            factorial =  factorial / 10;
            count++;
        }
        count = count - 1;
        if(count == p)
        {
            ok = 1;
            fprintf(oFile, "%llu", n);
        }
        n++;
        count = 0;
        ucif = 0;

    }
    fclose(iFile);
    fclose(oFile);
    return 0;
}