#include <fstream>

using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");

long long  n,i,v[1000005],d[1000005];

int main()
{
    fin>>n;
    for(i=1;i<=n;i++){
        fin>>v[i];
        if(v[i-1]<v[i])
            d[i]=d[i-1]+v[i]-v[i-1];
        else
            d[i]=d[i-1];
    }
    fout<<d[n];
    return 0;
}