Compilare: main.cpp: In function 'int main()': main.cpp:18:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("heavymetal.in", "r", stdin); ^ main.cpp:19:44: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("heavymetal.out", "w", stdout); ^ main.cpp:23:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &n); ^ main.cpp:25:43: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &v[i].st, &v[i].dr); ^ main.cpp:40:29: warning: 'r' may be used uninitialized in this function [-Wmaybe-uninitialized] vmax[i] = max(vmax[r] + v[i].dr - v[i].st, vmax[i - 1]); ~~~~~~^