#include <cstdio>
int p5[50],dim;
int main () {
	int n,i,c=0,vc,uv;
	
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&n);
	if(n==0){
		printf("1");
		return 0;
	}
	for(vc=1;vc<=100000000;vc*=5){
		p5[++dim]=vc;
	}
	//for(i=1;i<=15;++i)fprintf(stderr,"%d ",p5[i]);
	for(i=5;c<n;i+=5){
		uv=i;
		vc=1;
		for(;uv%p5[vc]==0;)++vc;
		vc-=2;
		c+=vc;
		
	}
	printf("%d",uv);
	return 0;
}