Compilare: main.cpp: In function 'int main()': main.cpp:13:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("grea.in", "r", stdin); ^ main.cpp:14:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("grea.out", "w", stdout); ^ main.cpp:16:51: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %s %s", &n, &k, a[0] + 1, a[1] + 1); ^