Compilare: user.c: In function ‘main’: user.c:15:11: warning: format ‘%lu’ expects argument of type ‘long unsigned int *’, but argument 2 has type ‘size_t * {aka unsigned int *}’ [-Wformat=] scanf("%lu %lu ", &n, &m); ^ user.c:15:11: warning: format ‘%lu’ expects argument of type ‘long unsigned int *’, but argument 3 has type ‘size_t * {aka unsigned int *}’ [-Wformat=] user.c:52:12: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘size_t {aka unsigned int}’ [-Wformat=] printf("%lu\n", r); ^ user.c:12:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("map.in", "r", stdin); ^ user.c:13:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("map.out", "w", stdout); ^ user.c:15:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lu %lu ", &n, &m); ^ user.c:18:9: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Wunused-result] fgets(s + 1, SIZE + 5, stdin); ^ In file included from /usr/include/stdio.h:936:0, from user.c:1: In function ‘fgets’, inlined from ‘main’ at user.c:18:9: /usr/include/bits/stdio2.h:261:9: 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); ^