#include <bits/stdc++.h>

using namespace std;
ifstream f("operatii.in");
ofstream g("operatii.out");

const int maxn = 1000005;

int v[maxn], n;

void read() {
    f >> n;
    for(int i = 1; i <= n; ++i) {
        f >> v[i];
    }
}

void solve() {
    read();
    unsigned long long output = 0;
    for(int i = 1; i <= n; ++i) {
        if(v[i] > v[i - 1]) {
            output += v[i] - v[i - 1];
        }
    }

    g << output << '\n';
}

int main() {
    solve();
}