#include <stdio.h>
#include <stdlib.h>

#define NMAX 5005
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y))

int N, a[NMAX], b[NMAX], c[NMAX], i, j, p[NMAX][NMAX], nb, start, end, aux;

int cmp(const void *a, const void *b)
{
    return ( *(int*)a - *(int*)b );
}

void print()
{
    for (i = 1; i <= nb; i++)
        printf("%d ", b[i]);
    printf("\n");

    for (i = 1; i <= nb; i++)
    {
        for (j = 1; j <= N; j++)
        {
            if (a[j] == b[i])
                printf("*%d ", p[i][j]);
            else
                printf("%2d ", p[i][j]);
        }
        printf("\n");
    }
    printf("\n");
}

int main()
{
    FILE *in, *out;
    in  = fopen("secv.in", "r");
    out = fopen("secv.out", "w");

    fscanf(in, "%d\n", &N);
    for (i = 1; i <= N; i++)
    {
        fscanf(in, "%d", a+i);
        c[i] = a[i];
    }
    qsort(&c[1], N, sizeof(int), cmp);

    nb = 1;
    b[nb] = c[1];
    for (i = 2; i <= N; i++)
    {
        if (c[i] > b[nb])
            b[++nb] = c[i];
    }

    for (i = 1; i <= nb; i++)
    for (j = 1; j <= N; j++)
    {
        if (a[j] == b[i])
            p[i][j] = 1 + p[i-1][j-1];
        else
            p[i][j] = MAX(p[i-1][j], p[i][j-1]);
    }

    if (p[nb][N] < nb)   //fara solutie
    {
        fprintf(out, "0\n");
        goto done;
    }

    j = N;
    while(p[nb][j] == nb)
        j--;
    end = j;

    i = nb-1, j = end-1;
    while (i)
    {
        if (a[j] == b[i])
        {
            start = i;
            j--, i--;
        }
        else
            j--;
    }
   
    fprintf(out, "%d\n", end-start+1);
done:

    fclose(in);
    fclose(out);
    return 0;
}