Compilare: user.cpp: In function ‘void solve()’: user.cpp:49:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(k<strlen(sir)) ^ user.cpp:54:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[k]!='+'&&k<strlen(sir)) ^ user.cpp:24:36: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d%c", &n, &m, &ch); ^ user.cpp:27:31: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] { fgets(mat[i], MaxM, in); ^