#include <iostream>
using namespace std;
int main(){
int N;
int vetor[1005];
cin >> N;
for(int i = 0;i<N;i++){
cin >> vetor[i];
}
int resposta = 1;
for(int i = 2; i < N; i++){
if( (vetor[i]-vetor[i-1]) !=
(vetor[i-1]-vetor[i-2]) ){
resposta++;
}
}
cout << resposta << endl;
}
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