#include <cstdio>

using namespace std;

#define FIN "operatii.in"
#define FOUT "operatii.out"
#define MAX_N 1000005

//int V[MAX_N];
int A, B;
int N, i;
long long Best;

    int main ()
    {
        freopen (FIN, "r", stdin);
        freopen (FOUT, "w", stdout);
        
        scanf ("%d", &N);
        scanf ("%d", &A);
        for (i = 1; i <= N; ++i) 
        {
            scanf ("%d", &B);
            if (B > A) Best+=(long long)(B - A);
            A = B;
        }
       /* 
        for (i = 1; i <= N; ++i) 
            if (V[i] > V[i - 1]) Best+= (long long)(V[i] - V[i - 1]);
        */
        printf ("%lld\n", Best);
        
        return 0;
    }