Luogu P1969 [NOIp提高组2013]积木大赛

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main(){
int n;
scanf("%d",&n);
int ans=0,a,last=0;
for(int i=0;i<n;++i){
scanf("%d",&a);
if(last<a) ans+=a-last;
last=a;
}
printf("%d",ans);
return 0;
}