In the - sit venia verbo - Art of Programming, one is frequently faced with the task to determine if elements in a list agree with each other; for example, when a magma given by its Cayley table is checked for cancelability, or when in a data base, e.g. of personnel files, equal attributes have to be detected. Essentially, this task amounts to detect whether a finite sequence of positive integers has equal elements. We elaborate on the complexity of this problem.