#include<stdio.h>
FILE *f,*g;
long sem=1,n=1,i,p,nr=1,q=1;
int main() {
f=fopen("fact.in","r");
fscanf(f,"%ld",&p);
fclose(f);
g=fopen("fact.out","w");
for(i=1;i<=p;i++) nr=nr*10;
if(nr!=1) while(sem==1){ if(q%nr==0) { sem=0;
			   fprintf(g,"%ld",n); }
	       else { n++;
	        	    q*=n; }  }
else fprintf(g,"%ld",n);
fclose(g);
return 0;
}