#include <cstdio>
#include <fstream>
#define nmax 1000005
using namespace std;
long long sol;
int n,v[nmax];


class instream {
    public:
        instream() {}
        instream(const char *file_name) {
            input_file=fopen(file_name,"r");
            cursor=0;
            fread(buffer,SIZE,1,input_file);
        }
        inline instream &operator >>(int &n) {
            while(buffer[cursor]<'0'||buffer[cursor]>'9') {
                advance();
            }
            n=0;
            while('0'<=buffer[cursor]&&buffer[cursor]<='9') {
                n=n*10+buffer[cursor]-'0';
                advance();
            }
            return *this;
        }
    private:
        FILE *input_file;
        static const int SIZE=1<<15;
        int cursor;
        char buffer[SIZE];
        inline void advance() {
            ++ cursor;
            if(cursor==SIZE) {
                cursor=0;
                fread(buffer,SIZE,1,input_file);
            }
        }
};
instream f("operatii.in");
ofstream g("operatii.out");



int main()
{
    f>>n;
    for (int i=1;i<=n;i++) {
        f>>v[i];
        if (v[i]>v[i-1])
            sol+=v[i]-v[i-1];
    }
    g<<sol;
    return 0;
}