#include<cstdio>
int n,a[1<<20];
void read()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
}
void solve()
{
    long long c=0;
    for(int i=1;i<=n;i++)
        if(a[i]>a[i-1])
            c+=(long long)a[i]-a[i-1];
    printf("%lld",c);
}
int main()
{
    read();
    solve();
    return 0;
}