#include <fstream>

using namespace std;

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

typedef long long i64;

int main(  ) {
    int n;
    fin>>n;
    int x= 0, y= 0;
    i64 sol= 0;
    for ( int i= 0; i<n; ++i ) {
        y= x;
        fin>>x;
        if ( x>y ) {
            sol+= x-y;
        }
    }
    
    fout<<sol<<"\n";

    return 0;
}