#include <cstdio>
#include <cstdlib>
#include <algorithm>
using namespace std;

int N, Last, Now;
long long Ans;

int main()
{
    freopen("operatii.in", "r", stdin);
    freopen("operatii.out", "w", stdout);
    
    scanf("%i", &N);
    for(int i = 1; i <= N; ++ i)
    {
        scanf("%i", &Now);
        if(Now > Last) Ans += Now - Last;
        Last = Now;
    }
    printf("%lld\n", Ans);
    
    return 0;
}