Compilare: user.cpp: In function ‘int main()’: user.cpp:73:32: 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:77:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S); ^ user.cpp:83:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S); ^ /tmp/ccec4GQR.o: In function `main': user.cpp:(.text.startup+0x4b): warning: the `gets' function is dangerous and should not be used.