题解

#include <bits/stdc++.h>
using namespace std;
long long n, x, y;
long long get_gezi_number(long long n, long long x, long long y) {
    long long cnt = 0;
    long long d = min( min(x-1, n-x), min(y-1, n-y) );
    cnt = ( 4 * n - 4 + 4 * (n-2*d+2) - 4 ) * d / 2;
    long long x1 = d+1, Y1 = d+1, x2 = n-d, y2 = n-d;
    if (x1 == x) cnt += y-Y1+1;
    else if (y2 == y) cnt += (n-2*d-1) + x-x1+1;
    else if (x2 == x) cnt += 2 * (n-2*d-1) + y2-y+1;
    else cnt += 3 * (n-2*d-1) + x2-x+1;
    return cnt;
}
int main() {
    cin >> n >> x >> y;
    cout << get_gezi_number(n, x, y) << endl;
    return 0;
}