#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <cmath>
#include <iomanip>
#include <map>
using namespace std;
typedef long long LL;

int main(){
    LL x, y, d;
    cin >> x >> y >> d;
    if(x+y < d){
        cout << 0 << endl;
    }else if(x+y == d){
        cout << 1 << endl;
    }else{
        cout << d+1 - max<LL>(0, d - x) - max<LL>(0, d - y) << endl;;
    }
    return 0;
}