#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define llong long long

int main() {
    uint x, y, d;
    cin >> x >> y >> d;

    bool left = y >= d;
    bool top = d > y && d <= x + y;
    bool right = d >= x && d <= x + y;
    bool bottom = d < x;

    if(left || top) {
        int x0, x1;
        x0 = left ? 0 : d - y;
        x1 = bottom ? d : y;
        cout << x1 - x0 + 1 << endl;
    } else {
        cout << 0 << endl;
    }
}