poj 3250 单调栈 *

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
#include<stack>
using namespace std;
#define MOD 1000000007
const int INF=0x3f3f3f3f;
const double eps=1e-5;
typedef long long ll;
#define cl(a) memset(a,0,sizeof(a))
#define ts printf("*****\n");
const int MAXN=80005;
int n,m,tt;
int st[MAXN];
int main()
{
int i,j,k;
#ifndef ONLINE_JUDGE
freopen("1.in","r",stdin);
#endif
while(~scanf("%d",&n))
{
int top=0;
ll sum=0;
for(i=0;i<n;i++)
{
int a;
scanf("%d",&a);
while(top>0&&st[top-1]<=a)   top--;
sum+=top;
st[top++]=a;
}
printf("%lld\n",sum);
}
}