#include <fstream>

#define in "subsir2.in"
#define out "subsir2.out"
#define Max_Size 5009
#define oo 1000000

std :: ifstream f(in);
std :: ofstream g(out);

int N, minim, A[Max_Size], DP[Max_Size];
bool Viz[Max_Size];

int main() {
    f >> N;
    for(int i = 1; i <= N; ++i) f >> A[i];

    DP[N] = 1;
    for(int i = N - 1; i >= 1; --i) {
        minim = DP[i] = oo;
        for(int j = i + 1; j <= N; ++j) {
            if(A[i] <= A[j] && minim > A[j]) {
                minim = A[j];
                if(DP[i] > DP[j] + 1)   DP[i] = DP[j] + 1;
            }
            if(A[i] <= A[j])    Viz[j] = 1;
        }
    }
    int minim = oo;
    for(int i = 1; i <= N; ++i)
        if(minim > DP[i] && !Viz[i])    minim = DP[i];

    g << minim << '\n';
    g.close();
    return 0;
}