#include <cstdio>  
 int main()  
 {  
     unsigned int p = 0, N, i, c;  
     unsigned long long s = 0;  
     freopen("operatii.in", "r", stdin);  
     freopen("operatii.out", "w", stdout);  
     scanf("%d\n", &N);  
     for (i = 0; i != N; ++i) {  
         scanf("%d", &c);  
         if (c > p) s += c - p;  
         p = c;  
     }  
     printf("%llu\n", s);  
     return 0;  }