Compilare: main.cpp: In function 'int main()': main.cpp:15:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("mine.in", "r", stdin); ^ main.cpp:16:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("mine.out", "w", stdout); ^ main.cpp:17:24: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(c, sz, stdin); s=-1; ^ main.cpp:22:28: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(c, sz, stdin); s=-1; ^ main.cpp:28:24: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(c, sz, stdin); s=-1; ^ main.cpp:30:30: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] s=-1; fgets(c, sz, stdin); ^