#include<iostream>
#include<string>

using namespace std;

int main()
{
    long long sum=0;
    int n;
    
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    
    scanf("%d",&n);
    
    int i,prev=0,c;
    
    for(i=1;i<=n;i++)
    {
      scanf("%d",&c);
      if(c<prev) sum+=(prev-c);
      prev=c;
    }
    
    sum+=prev;
    
    printf("%lld",sum);
    
    return 0;
}