Compilare: main.cpp: In function 'int main()': main.cpp:9:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("diviz.in", "r", stdin); ^ main.cpp:10:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("diviz.out", "w", stdout); ^ main.cpp:12:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d\n", &k, &x, &y); ^ main.cpp:13:24: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(a+1, N+5, stdin); a[0]='!'; n=strlen(a)-2; ^ In file included from /usr/include/stdio.h:936:0, from /usr/include/c++/6/cstdio:42, from main.cpp:1: In function 'char* fgets(char*, int, FILE*)', inlined from 'int main()' at main.cpp:13:24: /usr/include/x86_64-linux-gnu/bits/stdio2.h:261:58: warning: call to '__fgets_chk_warn' declared with attribute warning: fgets called with bigger size than length of destination buffer return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^