`\color{red}{\text{@hoangduy67}}`

#include <iostream>
using namespace std;

int main() {
    int x, y, z;
    cin >> x >> y >> z;

    if (y + z >= x) {
        cout << "Khong can them phieu bau";
    } else {
        cout << "Can them it nhat " << 2 * (y + z) - x << " phieu bau";
    }

    return 0;
}

#include <bits/stdc++.h>

using namespace std;

int main()
{
    int a, b, c;
    cin >> a >> b >> c;
    cout << max(max(b, c) - a + 1, 0);
    return 0;
}