#include<fstream>
using namespace std;
int x, n, i, maxim, u;
long long s;
FILE*fin=fopen("operatii.in","r");
ofstream fout("operatii.out");
int main(){
    fscanf(fin,"%d", &n);
    for(i=1; i<=n; i++){
        fscanf(fin,"%d", &x);
        if(x>u){
            s+=x-u;
        }
        u=x;
    }
    fout<<s;
return 0;
}