#include <iostream>
#include <vector>
#include <map>
#include<string>
#define ll long long
using namespace std;
int main() {
    ll x,y,z;
    cin>>x>>y>>z;
    ll ans=z;
    if(z>=x and z>0) ans-=1;
    if(z>=y and z>0) ans-=1;
    cout<<ans<<endl;
    return 0;
}