Compilare: main.cpp:10:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main(){ ^ main.cpp: In function 'int main()': main.cpp:11:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.in","r",stdin); ^ main.cpp:12:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.out","w",stdout); ^ main.cpp:13:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m);n--; ^