思路：

ACcode: 

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e5+10;
int n,a[N],ans;
void solve() {
  cin>>n;
  for(int i=1;i<=n;i++)cin>>a[i];
   
   int ans=0;
   for(int i=1;i<=n;i++){
   	if(a[i]>a[i-1]) ans+=a[i]-a[i-1];
   }
   cout<<ans<<"\n";
}
signed main() {
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	int t=1;
	//cin>>t;
	while(t--) {
		solve();
	}
	return 0;
}

over~