#include <fstream>
int n,v[1000002],i=1;long long r;int main(){std::ifstream f("operatii.in");f>>n;for(;i<=n;i++){f>>v[i];if(v[i]>v[i-1])r+=v[i]-v[i-1];}std::ofstream("operatii.out")<<r;return 0;}