#include<bits/stdc++.h>
using lint=long long;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint x,y,d;std::cin>>x>>y>>d;
    std::cout<<std::max(0ll,std::min(x,d)-std::max(0ll,d-y)+1)<<'\n';
}