#include <stdio.h>
#define PRICE 10
int main(){
int N,num=0;
scanf("%d",&N);
while(N>=10){
if(N>=5*PRICE){
N-=5*PRICE;
num+=7;
}
else if(N>=3*PRICE){
N-=3*PRICE;
num+=4;
}
else{
N-=PRICE;
num++;
}
}
printf("%d",num);
return 0;
}