#include <iostream>
using namespace std;

using int64 = long long;

int main() {
    int64 X, Y, D;
    cin >> X >> Y >> D;

    int64 x = max(0LL, D - Y);
    int64 y = max(0LL, D - X);
    int64 x2 = D - y;

    if (x > X or y > Y) {
        cout << 0 << endl;
        return 0;
    }

    cout << x2 - x + 1 << endl;

    return 0;
}