#include <cstdio>
#include <cctype>
using namespace std;
const int MOD = 666013;
const int MAXN = 1000000;
int ans[MAXN + 5], aux[MAXN + 5];
class InParser {
private:
    FILE *fin;
    char *buff;
    int sp;

    char read_ch() {
        ++sp;
        if (sp == 4096) {
            sp = 0;
            fread(buff, 1, 4096, fin);
        }
        return buff[sp];
    }

public:
    InParser(const char* nume) {
        fin = fopen(nume, "r");
        buff = new char[4096]();
        sp = 4095;
    }

    InParser& operator >> (int &n) {
        char c;
        while (!isdigit(c = read_ch()) && c != '-');
        int sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }

    InParser& operator >> (long long &n) {
        char c;
        n = 0;
        while (!isdigit(c = read_ch()) && c != '-');
        long long sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }
};
class OutParser {
private:
    FILE *fout;
    char *buff;
    int sp;

    void write_ch(char ch) {
        if (sp == 50000) {
            fwrite(buff, 1, 50000, fout);
            sp = 0;
            buff[sp++] = ch;
        } else {
            buff[sp++] = ch;
        }
    }


public:
    OutParser(const char* name){
      fout = fopen(name, "w");
      buff = new char[50000]();
      sp = 0;
    }
    ~OutParser(){
      fwrite(buff, 1, sp, fout);
      fclose(fout);
    }
    OutParser& operator << (int vu32){
      if (vu32 <= 9){
        write_ch(vu32 + '0');
      }else{
        (*this) << (vu32 / 10);
        write_ch(vu32 % 10 + '0');
      }
      return *this;
    }
    OutParser& operator << (long long vu64){
      if (vu64 <= 9){
        write_ch(vu64 + '0');
      }else{
        (*this) << (vu64 / 10);
        write_ch(vu64 % 10 + '0');
      }
      return *this;
    }
    OutParser& operator << (char ch){
      write_ch(ch);
      return *this;
    }
    OutParser& operator << (const char *ch){
    while (*ch){
        write_ch(*ch);
        ++ch;
    }
    return *this;
  }
};
int main(){
  InParser fin("operatii.in");
  OutParser fout("operatii.out");
  int n, i, a, b;
  long long ans;
  fin >> n;
  ans = a = 0;
  for (i = 1; i <= n; i ++){
    fin >> b;
    if (b > a)
      ans += b - a;
    a = b;
  }
  fout << ans;
  return 0;
}