# PROBLEM LINK:

Practice

Contest: Division 1

Contest: Division 2

Contest: Division 3

Contest: Division 4

* Author:* notsoloud

*satyam_343*

**Tester:***iceknight1093*

**Editorialist:**# DIFFICULTY:

272

# PREREQUISITES:

None

# PROBLEM:

A blood drive aims to collect N donations, of which X have been collected so far.

How many more are needed to reach their target?

# EXPLANATION:

X out of N donations are done, which leaves N-X remaining.

So, the answer is N-X.

# TIME COMPLEXITY

\mathcal{O}(1) per testcase.

# CODE:

## Editorialist's code (Python)

```
testcases = int(input())
for t in range(testcases):
n, x = map(int, input().split())
print(n - x)
```