#include <bits/stdc++.h>
#define REP(i, n) for(int i=0;i<(n);++i)
#define LL long long
using namespace std;

int main(void) {
  LL L, R, M;
  cin >> L >> R >> M;
  int ans = min(R-L+1, M);
  cout << ans << endl;
}