#include <cstdio>

using namespace std;

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

int V[MAX_N];
int N, i;
long long Best;

    int main ()
    {
        freopen (FIN, "r", stdin);
        freopen (FOUT, "w", stdout);
        
        scanf ("%d", &N);
        for (i = 1; i <= N; ++i) scanf ("%d", V + i);
        
        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;
    }