#include <cstdio>

int f(int a){
	if(a==1)
		return 1;
	else return a*f(a-1); 
}
int nfive(int a){
	int nf=0;
	while(a%5==0&&a!=0){
		a/=5;
		nf++;
	}
	return nf;
}
int main(){
	int P,N=0;
	FILE *fin,*fout;
	fin=fopen("fact.in","r");
	fout=fopen("fact.out","w+");
	fscanf(fin,"%u",&P);
	fclose(fin);
	if(P==0){
		N=1;
	}else{
		int tf=0;
		for(int i=0;i<100000000;i+=5){
			printf("%u\n",nfive(i));
			tf+=nfive(i);
			if(tf==P){
				N=i;
				break;
			}else if(tf>P){
				N=-1;
			}
		}
	}
	fprintf(fout,"%u",N);
	fclose(fout);
}