#include<stdio.h>
FILE*A,*B;
long long unsigned v[1000003],i,nr=0,n;
int main()
{
	A=fopen("operatii.in","r");
	B=fopen("operatii.out","w");
	fscanf(A,"%llu",&n);
	v[0]=0;
	for(i=1;i<=n;i++)
	{
		fscanf(A,"%llu",&v[i]);
		if(v[i]>v[i-1])nr=nr+v[i]-v[i-1];
	}
	fprintf(B,"%llu",nr);
}