#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
int n;
int h[100010];
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>h[i];
    }
    int hh=h[1],ans=h[1];
    for(int i=2;i<=n;i++){
        if(h[i]>hh) ans += h[i]-hh;
        hh = h[i];
    }
    cout<<ans;
    return 0;
}