#include <stdio.h>
FILE *fin, *fout;
int n, c, c1;
long long int s;
int main()
{
    fin = freopen("operatii.in", "r", stdin);
    fout = freopen("operatii.out", "w", stdout);
    scanf("%d", &n);
    for(int i = 0; i< n; i++)
    {
            scanf("%d", &c);
            if(c > c1) s+=1LL*(c-c1);
            c1 = c;
    }
    printf("%lld\n", s);
    fclose(fin);
    fclose(fout);
    return 0;
}