// Print the string s to standard output
function print : (string s)

// print the integer i to standard output
// Equivalent to print(itos(i))
function printi : (int i)

// Print character whose ASCII code is c to strandard output
function printc : (int c)

// Read a line from standard input
function readln : () -> string

// Read a character from standard input
function readc : () -> int

// Return true if standard input has reached end of file
function eof : () -> bool