#include <cstdio>
using namespace std;
int n,m,i,j,s,nr,x,y;
int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        scanf("%d",&x);
        s=0;
        if(x>y)
        {
            s=x-y;
            nr+=s;
        }
        y=x;
    }
    printf("%d\n",nr);
    return 0;
}