#include <fstream.h>

int main(){
    ifstream in("operatii.in");
    ofstream out("operatii.out");
    long long int  n,sum=0,i,nr,max=0,temp=0;
    in >>n;
    for(i=0;i<n;i++){
                     in >>nr;
                     if(nr>temp)
                                sum=sum+(nr-temp);
                     temp=nr;
                    

    }
    out <<sum;
    in.close();
    out.close();
    return 0;
}