Compilare: user.cpp: In function ‘int main()’: user.cpp:53:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(S); N = strlen(S); ^~~~ In file included from /usr/include/c++/6/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^~~~ user.cpp:53:11: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(S); N = strlen(S); ^ In file included from /usr/include/c++/6/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^~~~ user.cpp:50:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("risipa.in", "r", stdin); ^ user.cpp:51:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("risipa.out", "w", stdout); ^ user.cpp:53:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S); N = strlen(S); ^ user.cpp:56:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &A, &B); ^ /tmp/cc2Zm6ep.o: In function `main': user.cpp:(.text.startup+0x49): warning: the `gets' function is dangerous and should not be used.