#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,a[100005],ans;
signed main()
{
cin>>n;
for(int i=1;i<=n;i++) cin>>a[i];
for(int i=1;i<=n&&a[i]!=0;)
{
ans++;
int j=i;
while(j+1<=n&&a[j+1]!=0) j++;
for(int k=i;k<=j;k++) a[k]--;
while(a[i]==0&&i<n)i++;
}
cout<<ans;
return 0;
}

#include<bits/stdc++.h>
using namespace std;
int a[100001];
int main()
{
int n,ans=0; cin>>n;
for(int i=1;i<=n;i++) cin>>a[i];
for(int i=1;i<=n;i++)
if(a[i]>a[i-1])
ans+=(a[i]-a[i-1]);
cout<<ans;
return 0;
}