#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int read(){
    int t=1,num=0;
    char c=getchar();
    while(c>‘9‘||c<‘0‘){if(c==‘-‘)t=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){num=num*10+c-‘0‘;c=getchar();}
    return num*t;
}
int a,n,ans=0,last=0;
int main()
{
    n=read();
    for(int i=1;i<=n;i++){
        a=read();
        if(a>last)ans+=a-last;
        last=a;
    }
    printf("%d",ans);
    return 0;
}