#include using namespace std; typedef long long ll; typedef vector VI; typedef vector VVI; typedef vector VL; typedef vector VVL; typedef pair PII; #define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i) #define REP(i, n) FOR(i, 0, n) #define ALL(x) x.begin(), x.end() #define MOD 1000000007 #define INF (1LL<<25) //33554432 #define PI 3.14159265359 #define EPS 1e-12 //#define int ll signed main(void) { ll x, y, d; cin >> x >> y >> d; if(x>=d && y>=d) cout << d+1 << endl; else if(x+y < d) cout << 0 << endl; else cout << x+y-d+1 << endl; return 0; }