Compilare: main.cpp: In function 'int main()': main.cpp:27:24: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d\n",&t); ^ main.cpp:31:28: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d\n",&k); ^ main.cpp:32:32: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(a + 1,NMAX + 5,f);len_a = strlen(a + 1);len_a -= (a[len_a] == '\n'); ^ main.cpp:33:32: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(b + 1,NMAX + 5,f);len_b = strlen(b + 1);len_b -= (b[len_b] == '\n'); ^ 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:32:32: /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); ^ In function 'char* fgets(char*, int, FILE*)', inlined from 'int main()' at main.cpp:33:32: /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); ^