#include <stdio.h>
int a[1000001],nr,n;
int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    scanf("%d\n",&n);
    int i;
    for (i=1;i<=n;i++)
    {
        scanf("%d",&a[i]);
        if (a[i]>a[i-1])
            nr+=a[i]-a[i-1];
    }
    printf("%d\n",nr);
    return 0;
}