#include<iostream>
using namespace std;
int main(){
	int x,y,n;
	cin>>x>>y>>n;
	cout <<n-0.9*(x+y)<<endl;
	return 0;
}
/**************************************************************
	Problem: 1598
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/