Compilare: main.cpp: In function 'int main()': main.cpp:61:19: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] s[i][n+1]=NULL; ^~~~ main.cpp:54:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("barbar.in","r",stdin); ^ main.cpp:55:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("barbar.out","w",stdout); ^ main.cpp:57:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n",&m,&n); ^ main.cpp:60:33: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(s[i]+1,1005,stdin); ^