#include<iostream>
int n,a[100001],ans;
int main()
{
    std::cin>>n;
    for(int i=1;i<=n;i+=1)
    {
        std::cin>>a[i];
        if(a[i]>a[i-1])ans+=a[i]-a[i-1];
    }
    std::cout<<ans<<std::endl;
}