//#include <atcoder/all>
#include <iostream>
#include <numeric>
#include <cmath>
#include <limits>
#include <stdio.h>
#include <iomanip>
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
using namespace std;
//using namespace atcoder;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;

vector<priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>>> edge;
vector<bool> seen;
vll AN;
ll p = 1;
ll N;
void dfs(const Graph & G, int v) {
	seen[v] = true; // v を訪問済にする
	AN[v] = p;
	// v から行ける各頂点 next_v について
	while (!edge[v].empty()) {
		ll next_v = edge[v].top().second;
		edge[v].pop();
		if (seen[next_v]) continue; // next_v が探索済だったらスルー
		p++;
		dfs(G, next_v); // 再帰的に探索
		p++;
	}

}
vll kB;
ll j = 0;
ll tt = 0;
void predfs(const Graph& G, int v) {
	tt++;
	seen[v] = true; // v を訪問済にする
	AN[v] = p;
	ll now = tt;
	j++;
	
	// v から行ける各頂点 next_v について
	ll pe = 0;
	for (auto next_v : G[v]) {
		pe++;
		if (seen[next_v]) continue; // next_v が探索済だったらスルー
		/*if (pe == G[v].size()) {
			edge[v].push(make_pair(N-now, next_v));
		}*/
		
		ll M = j;
		predfs(G, next_v); // 再帰的に探索
		
		edge[v].push(make_pair(j - M, next_v));
	}

}
int main() {
	ll X, Y, D;
	cin >> X >> Y >> D;
	if (X < Y)swap(X, Y);
	if (D <= Y) {
		cout << D+1 << endl;
	}
	else if (D <= X) {
		cout << Y + 1 << endl;
	}
	else if(D<=X+Y){
		cout << Y-(D-X)+1;
	}
	else {
		cout << 0 << endl;
	}

}