#include <cstdio>
using namespace std;

int main(){
  FILE *in = fopen("operatii.in", "r");
  int n, i, l = 0, x;
  long long rez = 0;
  fscanf(in, "%d", &n);
  for(i = 0; i < n; i++){
    fscanf(in, "%d", &x);
    if(x > l)
      rez += x - l;
    l = x;
  }
  fclose(in);
  FILE *out = fopen("operatii.out", "w");
  fprintf(out, "%lld", rez);
  fclose(out);
  return 0;
}