#include<stdio.h>
#define nmax 1000010

int v[nmax];
int n,max,nrop;

void read()
{
     int i;
     freopen("operatii.in","r",stdin);
     freopen("operatii.out","w",stdout);
     scanf("%d", &n);
     for(i=1; i<=n; ++i)
        scanf("%d", &v[i]);
}


void solve()
{
   int i;
   for(i=1; i<=n; i++)
     if(v[i]>v[i-1])
       nrop=nrop+v[i]-v[i-1];
       
}

void print()
{
     printf("%d\n", nrop);
}

int main()
{
     read();
     solve();
     print();
     return 0;
}