题目:https://www.luogu.org/problemnew/show/P1969
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int n,a,b,ans;
int main()
{
scanf("%d",&n);
for(int i=1;i<=n;i++)
{
scanf("%d",&a);
ans+=max(0,a-b);
b=a;
}
printf("%d\n",ans);
return 0;
}