#include<stdio.h>
long nr,p;
long nz(long p)
{long nr=0;
 while(p%5==0) {nr++;  p=p/5;}
 return nr;}
long nrzero(long n,long nri,long p)
{long nr=nri;
 for(long i=p-p%5+5;i<=n;i=i+5)
  nr=nr+1+nz(i/5);
 return nr;}
long div(long inc,long sf,long nr)
{long m=(inc+sf)/2,nz;
 nz=nrzero(m,nr,inc);
 if(nz==p) return m;
 if(nz<p) return div(m,sf,nz);
 return div(inc,m,nr);
}
int main()
{freopen("fact.in","r",stdin);
 scanf("%ld",&p);
 fclose(stdin);
 if(p==0) nr=1;
 if(p<1000) nr=div(1,4005,0);
 if(p==1000) nr=4005;
 if(p>1000&&p<10000) nr=div(4005,40010,1000);
 if(p==10000) nr=40010;
 if(p>10000&&p<100000) nr=div(40010,400005,10000);
 if(p==100000) nr=400005;
 if(p>100000&&p<1000000)nr=div(400005,4000005,100000);
 if(p==1000000) nr=4000005;
 if(p>1000000&&p<5000000) nr=div(4000005,20000005,1000000);
 if(p==5000000) nr=20000005;
 if(p>5000000&&p<10000000) nr=div(20000005,40000010,5000000);
 if(p==10000000) nr=40000010;
 if(p>10000000&&p<15000000) nr=div(40000010,60000010,10000000);
 if(p==15000000) nr=60000010;
 if(p>15000000&&p<20000000) nr=div(60000010,80000015,15000000);
 if(p==20000000) nr=80000015;
 if(p>20000000&&p<25000000) nr=div(80000015,100000005,20000000);
 if(p==25000000) nr=100000005;
 if(p>25000000&&p<30000000) nr=div(100000005,120000010,25000000);
 if(p==30000000) nr=120000010;
 if(p>30000000&&p<35000000) nr=div(120000010,140000015,30000000);
 if(p==35000000) nr=140000015;
 if(p>35000000&&p<40000000) nr=div(140000015,160000015,35000000);
 if(p==40000000) nr=160000015;
 if(p>40000000&&p<45000000) nr=div(160000015,180000015,40000000);
 if(p==45000000) nr=180000015;
 if(p>45000000&&p<50000000) nr=div(180000015,200000010,45000000);
 if(p==50000000) nr=200000010;
 if(p>50000000&&p<55000000) nr=div(200000010,220000015,50000000);
 if(p==55000000) nr=220000015;
 if(p>55000000&&p<60000000) nr=div(220000015,240000020,55000000);
 if(p==60000000) nr=240000020;
 if(p>60000000&&p<65000000) nr=div(240000020,260000010,60000000);
 if(p==65000000) nr=260000010;
 if(p>65000000&&p<70000000) nr=div(260000010,280000015,65000000);
 if(p==70000000) nr=280000015;
 if(p>70000000&&p<75000000) nr=div(280000015,320000015,70000000);
 if(p==80000000) nr=320000015;
 if(p>75000000&&p<80000000) nr=div(280000015,300000010,75000000);
 if(p==80000000) nr=300000010;
 if(p>80000000&&p<85000000) nr=div(300000010,340000015,80000000);
 if(p==85000000) nr=340000015;
 if(p>85000000&&p<90000000) nr=div(340000015,360000015,85000000);
 if(p==90000000) nr=360000015;
 if(p>90000000&&p<95000000) nr=div(360000015,370000015,90000000);
 if(p==92500000) nr=370000015;
 if(p>92500000&&p<95000000) nr=div(370000015,380000020,92500000);
 if(p==95000000) nr=380000020;
 if(p>95000000&&p<975000000) nr=div(380000020,390000020,95000000);
 if(p==975000000) nr=390000020;
 if(p>97500000&&p<100000000) nr=div(390000020,400000015,97500000);
 if(p==100000000) nr=400000015;
 while(nr!=1&&nr%5) nr--;
 freopen("fact.out","w",stdout);
 printf("%ld",nr);
 fclose(stdout);
 return 0;}