#include <stdio.h>
int n,v[1000005];


int main()
{
	int op=0,i;
	
	FILE *in  = fopen("operatii.in","r");
	FILE *out = fopen("operatii.out","w");
	
	fscanf(in,"%d",&n);
	fscanf(in,"%d",&v[0]);
	op=v[0];
	for (i=1; i<n; i++)
	{
		fscanf(in,"%d",&v[i]);
		if (v[i]>v[i-1])
			op+=v[i]-v[i-1];		
	}
	
	fprintf(out,"%d\n",op);
	
	return 0;
}