#include<stdio.h>
int main(void){
int a,b,c,d,e,f,g;
c=0;
b=1;
scanf("%d",&a);
while(b==1){
c=c+1;
e=50*c*c+50*c+100;

if(a<e)
{
  b=2;  
}
}
g=c-1;
d=50*g*g+50*g+100;
f=(a-d)/c;


printf("%d",(g*100)+f); 
}