Compilare: main.cpp: In function 'int main()': main.cpp:47:35: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] if(ok == 0) {sol[0] = NULL; printf("-1"); break;} ^~~~ main.cpp:49:19: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] sol[NR] = NULL; ^~~~ main.cpp:11:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("kss.in", "r", stdin); ^ main.cpp:12:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("kss.out", "w", stdout); ^ main.cpp:14:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ main.cpp:16:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%lld", &n, &k); ^ main.cpp:17:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s + 1); ^