#include<stdio.h>
#define ll long long
int i,n,a,b;
long long num;
int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        scanf("%d",&b);
        if(b>a)
            num+=(ll)(b-a);
        a=b;
    }
    printf("%lld\n",num);
    return 0;
}