#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,y,n;
	cin>>x>>y>>n;
	//  老板因该找给花花的钱 
	cout<<n-x-y; 
	return 0;
}
/**************************************************************
	Problem: 1597
	User: chenyaohuo
	Language: C
	Result: Compile Error
****************************************************************/