#include <stdio.h>



int main()
{
	long int rez = 0;
	int v[100000];
	int flag = 0, k = 0, r = 0,x = 0,p = 0,i = 0, k2 = 0, j = 0;
	FILE *in, *out;
	in = fopen("fact.in","r");
	fscanf(in,"%ld",&p);
	fclose(in);
	out = fopen("fact.out","w");
	if(p==0)fprintf(out,"%ld",x);
	for(i = 1; i < 100000; i++)
	{
		v[i] = i;
		j = i;
		flag = 0;
		k = 0;
		while(flag == 0)
		{
			
			if((v[i])%5 == 0)
			{
				k++;
				v[i] = v[i]/5;
				if((v[i])%5 != 0)k++;
				flag = 0;
			}else flag = 1;		
		}	
		if(v[i] != i)v[i] = -k;
		if(v[i] < 0)	r += -v[i];
		else	r++;
		if(r >= p)	break;
	}
	
	fprintf(out,"%ld",j*5);
	fclose(out);
	return 0;
}