#include <stdio.h>
using namespace std;

#define in "operatii.in"
#define out "operatii.out"
#define dim 1000001

int N;
long long Nrsol=0;
int A[dim];

int main()
{
    freopen(in,"r",stdin);
    freopen(out,"w",stdout);
    
    scanf("%d", &N);
    for ( int i = 1; i <= N; i++ )
        scanf("%d", &A[i]);
    
    A[0] = 0;
    
    for ( int i = 1; i <= N; i++ )
    {
        if ( A[i] > A[i-1] ) Nrsol += A[i] - A[i-1];
    }
    
    printf("%lld", Nrsol);
}