#include <iostream>
using namespace std;
int main() {
int a,b,c,g;
cin>>a>>b>>c;
g = (a - b);
if(g < 0){
g= g - 1;
if(g + c > 0){
g = + 1;
}
}
g = g + c;
cout<<g;
return 0;
}
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