#include <stdio.h>
int main()
{
    long long i,j,k,n,nrtot=0;
    
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    
    scanf("%lld",&n);
    
    j=0;
    for (i=1; i<=n; i++)
    {
        scanf("%lld",&k);
        if (k>j) nrtot+=(k-j);
        j=k;
    }    
    
    printf("%lld\n",nrtot);
    
    
    return 0;    
}