Different Signs
Programming Basics · Python
TASK
Problem
Given two non-zero integers `a`, `b`, print `YES` if their signs differ, else `NO`.
EXAMPLE
Example
4 -9
YES
LIMITS
Constraints
a ≠ 0; b ≠ 0
LEARN
Theory for this problem
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`input()` reads data entered by the user. The result of `input()` is initially a string. `split()` separates one input line into individual values using spaces. `map()` applies the specified conversion to each input value. Comparison operators `==`, `!=`, `<`, `>`, `<=`, `>=` compare values and produce `True` or `False`. `and` requires all combined conditions to be true. `or` requires at least one condition to be true. `if` checks a condition and runs its block when the condition is true. `else` runs when the corresponding `if` condition is false. `print()` displays the program result. Print only what the problem statement requires.
**Connection to this task.** An `if` statement chooses a program branch from a Boolean condition. Comparisons produce `True` or `False`, and `elif` lets you test several mutually exclusive cases in order. The expression `'YES'` shows how this idea is applied to the task data.
For this task, pay special attention to `map(int, input().split())`: it connects the concept above to the concrete computation or program action.
**Focus: “Different Signs”.** The same basic mechanism is used in a different context here, so understand the operation itself rather than memorizing a finished line of code.
NEED HELP?
Hints
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['One must be positive and the other negative.']
ANSWER
Solution
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a, b = map(int, input().split())
if a > 0 and b < 0 or (a < 0 and b > 0):
print('YES')
else:
print('NO')