#include<bits/stdc++.h>
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
int a[1000001],x,m,n,i,j,k,p1,p2,nr=0,mini;
unsigned long long maxi=0;
int main()
{fin>>n;
 for(i=1;i<=n;i++)
    fin>>a[i];
 i=1;
 while(i<=n)
 {if(a[i]!=0)
    {j=i+1;mini=a[i];
       while(a[j]!=0&&j<=n)
       {if(a[j]<mini)
           mini=a[j];
        j++;
       }
     for(k=i;k<=j-1;k++)
         a[k]=a[k]-mini;
    nr++;
    }else i++;
 }
 fout<<nr;
}