萌新蒟蒻败了 求神犇帮助

#include<bits/stdc++.h>
using namespace std;
int height[20000],n=0;
int main()
{
    int f1[21]={1},f2[21]={1};
    memset(height,0,sizeof(height));
    int n=0,i,j,k,unascend_l=0,undescend_l=0;
    while(cin>>height[n])
    {n++;}
    if(n==0) return 0;
    else{
    for(i=0;i<n;i++)
      for(j=i;j<n;j++)
        if(height[j]<=height[i]&&f1[j]>f1[i])
          f1[j]=f1[i]+1;
    for(i=0;i<n;i++)
      if(unascend_l<f1[i])
        unascend_l=f1[i];
    for(i=0;i<n;i++)
      for(j=i;j<n;j++)
        if(height[j]>height[i]&&f1[j]>f1[i])
          f2[j]=f2[i]+1;
    for(i=0;i<n;i++)
      if(undescend_l<f2[i])
        undescend_l=f2[i];
    cout<<unascend_l<<" "<<undescend_l<<endl;
    return 0;
    }
}