My MIPS program won't run in MARS I get an error "line 4 column 13: Symbol "txt1" not found in symbol table."

This is what it is supposed to do.

Write a MIPS assembly program that does the following:

1. Get three integers from the keyboard 2. Display the sum of the integers 3. Display the largest of the three values 4. Display the smallest of the three values 5. Allow multiple runs of the program

main: addi $s0, $zero, 0 loop: la $a0, txt1 li $v0, 4 syscall li $v0, 5 syscall bltz $v0, average add $s0, $v0, 0 add $t0, $t0, 1 add $t3, $t3, $s0 beq $t0, 1, first blt $s0, $t1, min bgt $s0, $t2, max first: add $t1, $s0, 0 add $t2, $s0, 0 j loop min: add $t1, $s0, 0 j loop max: add $t2, $s0, 0 j loop 

print: la $a0, txt2 li $v0, 4 syscall add $a0, $t2, 0 li $v0, 1 syscall la $a0, txt3 li $v0, 4 syscall add $a0, $t1, 0 li $v0, 1 syscall la $a0, txt4 li $v0, 4 syscall add $a0, $t7, 0 li $v0, 1 syscall exit: li $v0, 10 syscall