politic

#include <bits/stdc++.h>

using namespace std;

ifstream f("politic.in");
ofstream g("politic.out");

int n;
int v[20001], nrp;

int main()
{
    int i, j, x1, x2, nr = 1;

    f >> n >> x1;

    for(i = 2; i <= n; ++i){
        f >> x2;
        if(x2 - x1 == 1){
            ++nr;
        } else {
            v[++nrp] = nr;
            nr = 1;
        }

        x1 = x2;
    }

    v[++nrp] = nr;

    g << nrp << '\n';

    for(i = 2; i <= nrp; ++i){
        v[i] += v[i-1];
    }

    i = j = 1;
    int nrc = 0, med = n / 2;

    while(j <= nrp){
        if(v[j] - v[i - 1] > med){
            nrc += (nrp - j + 1);
            ++i;
        } else {
            ++j;
        }
    }

    g << nrc;

    return 0;
}