Compilare: user.cpp: In function ‘int main()’: user.cpp:58:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:59:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] for (i = 1; i <= n; ++ i) ^ user.cpp:60:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] { ^ user.cpp:63:28: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] a[i][j] = s[j] - '0'; ^ /tmp/ccheVJLc.o: In function `main': user.cpp:(.text.startup+0x88): warning: the `gets' function is dangerous and should not be used.