#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>

#define REP(i,n) for(long (i)=0;(i)<(n);(i)++)
#define FOR(i,a,b) for(long (i)=(a);(i)<(b);(i)++)
#define RREP(i,a) for(long (i)=(a)-1;(i)>=0;(i)--)
#define FORR(i,a,b) for(long (i)=(a)-1;(i)>=(b);(i)--)
#define MOD 1000000007
#define PI acos(-1.0)
#define DEBUG(C) cout<<C<<endl;
#define VI vector<int>
#define VL vector<long>
#define VD vector<double>
#define PII pair<int,int>
#define PDD pair<double,double>
#define PLL pair<long,long>
#define ALL(a) (a).begin(),(a).end()
#define SORT(a) sort((a).begin(),(a).end())
#define RSORT(a) sort((a).begin(),(a).end(),greater<int>())
#define MP(a,b) make_pair(a,b)
#define FORE(a,b) for(auto &&a:b)

typedef long long LL;
typedef unsigned long long ULL;

using namespace std;

long yy(long a,long x,long b){
    return a*x+b;
}

long xx(long a,long y,long b){
    return (y-b)/a;
}

int main(void){
    long x,y,d; cin>>x>>y>>d;
    if(!d || x+y==d){
        cout<<1<<endl; return 0;
    }
    if(x+y<d){
        cout<<0<<endl;
    }else{
        long ans=d+1;
        if(x>=d&&y>=d){
            cout<<ans<<endl;
        }else{
            if(x<d) ans-=(d-x);
            if(y<d) ans-=(d-y);
            cout<<ans<<endl;
        }
    }
}