#include <stdio.h>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <bitset>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <limits.h>
#include <set>
#define nmax 1000010
using namespace std;
int n,i,t[nmax];
long long sol=0;
int main(){
freopen("operatii.in","r",stdin);
freopen("operatii.out","w",stdout);
scanf("%d",&n);
for (i=1;i<=n;i++) scanf("%d",&t[i]);
for (i=1;i<=n;i++)
    if (t[i]>t[i-1]) sol=sol+(t[i]-t[i-1]);
printf("%lld",sol);
return 0;
}