Compilare: user.cpp: In function ‘void read()’: user.cpp:34:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bignumber.in", "r", stdin); ^ user.cpp:35:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bignumber.out", "w", stdout); ^ user.cpp:36:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &n, &m); ^ user.cpp:37:17: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(cp + 1); ^ /tmp/ccFUJLWy.o: In function `read()': user.cpp:(.text+0xe9): warning: the `gets' function is dangerous and should not be used.