#include<stdio.h>
int x,n,i,v[1000002];
long long nr;

int main(){
FILE *f=fopen("operatii.in","r");
fscanf(f,"%d",&n);
  for(i=1;i<=n;i++){
  fscanf(f,"%d",&v[i]);
  }
fclose(f);

v[0]=0;
nr=0;

  for(i=1;i<=n;i++){
   if(v[i]>v[i-1]){
   x=v[i]-v[i-1];
   nr+=x;
   }
  }




FILE *g=fopen("operatii.out","w");
fprintf(g,"%lld",nr);
fclose(g);


return 0;
}