#include<stdio.h>

int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    int n;
    scanf("%d",&n);
    int curent,precedent;
    long long sol=0;
    for(int i=1;i<=n;i++)
     {
         scanf("%d",&curent);
         if(curent>precedent)
           sol=sol+curent-precedent;
         precedent=curent;
     }
    printf("%lld\n",sol);
    return 0;
}