#include <cstdio>

using namespace std;

#define inFile "operatii.in"
#define outFile "operatii.out"
#define MAX_N 1000000

FILE *in = fopen(inFile, "r");
FILE *out = fopen(outFile, "w");

int V[MAX_N + 1];

int main() {
    int N, i, diff;
    long long nMoves = 0;
    
    fscanf(in, "%d", &N);
    for(i = 1; i <= N; i++) fscanf(in, "%d", &V[i]);
    
    for(i = 0; i < N; i++) {
        diff = V[i+1] - V[i];
        if(diff > 0) nMoves += diff;
    }
    
    fprintf(out, "%lld\n", nMoves);
    
    fclose(in);
    fclose(out);
    
    return 0;
}