#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
//---------------------------------------------------------------------------------------------------


int x, y, d;
//---------------------------------------------------------------------------------------------------
void _main() {
    cin >> x >> y >> d;

    if (x + y < d) printf("0\n");
    else if (d <= min(x, y)) printf("%d\n", d + 1);
    else {
        int L = max(0, d - y);
        int R = min(d, x);
        int ans = R - L + 1;
        printf("%d\n", ans);
    }
}