#include<stdio.h>
long n,i,a[10001];
long long rez;
int main(void)
{freopen("operatii.in","r",stdin);
freopen("operatii.out","w",stdout);
scanf("%ld",&n);
for(i=1;i<=n;i++)
scanf("%ld",&a[i]);
for(i=1;i<=n;i++)
if(a[i-1]<a[i])rez=rez+a[i]-a[i-1];
printf("%lld",rez);
return 0;}