傻逼了，程式碼裡面不知道在寫啥，總之答案是 ${\sum }_{i=1}^n\max$

#include<bits/stdc++.h>
#define gc getchar()
using namespace std;
inline int inn()
{
    int x,ch;while((ch=gc)<'0'||ch>'9');
    x=ch^'0';while((ch=gc)>='0'&&ch<='9')
        x=(x<<1)+(x<<3)+(ch^'0');return x;
}
const int N=100010;int s[N],top;
int main()
{
    int n=inn(),ans=0;
    for(int i=1,x;i<=n;i++)
    {
        x=inn(),ans+=max(x-s[top],0);
        while(top&&x>=s[top]) top--;s[++top]=x;
    }
    return !printf("%d\n",ans);
}