#include<fstream>
using namespace std;
ifstream fi("operatii.in");
ofstream fo("operatii.out");

long long sol=0;
int n,x,st=0;

int main(){
    fi>>n;
    
    for(;n>0;n--){
                  fi>>x;
                  if(x>st) sol+=(x-st);
                  st=x;
                 }
    
    fo<<sol;
    
    fi.close();
    fo.close();
    return 0;
}