#include<stdio.h>
#include<string.h>
long a,b,s,n,i,j;
FILE *f1,*f2;
int main(){
f1=fopen("operatii.in","r");
f2=fopen("operatii.out","w");
fscanf(f1,"%ld%ld",&n,&b);
s=b;
for(i=2;i<=n;i++){
	a=b;
	fscanf(f1,"%ld",&b);
	if(b-a>0){s=s+b-a;}
}
fprintf(f2,"%ld",s);
return 0;}