#include <iostream>
using namespace std;

int main(){
  int sic,sh,sm,eic,eh,em,st,et,S,E,flag,ans;
  int d[8][8];
  d[1][2]=d[2][1]=300;
  d[1][3]=d[3][1]=500;
  d[1][4]=d[4][1]=600;
  d[1][5]=d[5][1]=700;
  d[1][6]=d[6][1]=1350;
  d[1][7]=d[7][1]=1650;
  d[2][3]=d[3][2]=350;
  d[2][4]=d[4][2]=450;
  d[2][5]=d[5][2]=600;
  d[2][6]=d[6][2]=1150;
  d[2][7]=d[7][2]=1500;
  d[3][4]=d[4][3]=250;
  d[3][5]=d[5][3]=400;
  d[3][6]=d[6][3]=1000;
  d[3][7]=d[7][3]=1350;
  d[4][5]=d[5][4]=250;
  d[4][6]=d[6][4]=850;
  d[4][7]=d[7][4]=1300;
  d[5][6]=d[6][5]=600;
  d[5][7]=d[7][5]=1150;
  d[6][7]=d[7][6]=500;
  S=17*3600+30*60;
  E=19*3600+30*60;
  while(1){
    /*cin>>sic>>sh>>sm>>eic>>eh>>em;
    if(!sic) break;
    st=sh*3600+sm*60;
    et=eh*3600+em*60;
    flag=0;
    if((S<=st&&st<=E)||(S<=et&&et<=E)) flag=1;
    ans=d[sic][eic];*/
    //if(flag){
    int c;
    cin>>c;
    ans=c;
      int cal;
      ans/=2;
      cal=ans%100;
      if(cal%50){
	ans/=100;
	ans*=100;
	if(cal<50) ans+=50;
	else ans+=100;
      }
      //    }
    cout<<ans<<endl;
  }
  return 0;
}