#include<bits/stdc++.h>
using namespace std;
int main(){
	int s,a,b,h;
	cin>>a>>b>>h;
	s=h-(a+b);
	cout<<s;
}

/**************************************************************
	Problem: 1597
	User: huxuanchen
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/