Compilare: user.cpp: In function ‘void solve()’: user.cpp:102:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < E.size() ; j++){ ^ user.cpp: At global scope: user.cpp:139:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main(){ ^ user.cpp: In function ‘void read()’: user.cpp:65:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&R,&C); ^ user.cpp:68:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&board[i][j]); ^ user.cpp: In function ‘int main()’: user.cpp:142:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bemo.in","r",stdin); ^ user.cpp:143:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bemo.out","w",stdout); ^