#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i < b; i++)
#define rep(i, n) For(i, 0, n)
#define rFor(i, a, b) for(int i = a; i >= b; i--)
#define ALL(v) (v).begin(), (v).end()
#define rALL(v) (v).rbegin(), (v).rend()
using namespace std;

using lint = long long;
using ld = long double;

int INF = 2000000000;
lint LINF = 1000000000000000000;

int main() {
    int x, y, d;
    cin >> x >> y >> d;
    int l = max(0, d - y), r = min(x, d);
    cout << max(0, r - l + 1) << endl;
}