if the last 20 commit numbers are not in the current branch, the build(bitbucket pipeline) should fail

Question

if the last 20 commit numbers are not in the current branch, the transaction should fail my sh script.

    #!/bin/sh

masterCommit=$(git rev-list -n 20 master)
currentBranch=$(git rev-parse --abbrev-ref HEAD)
currentCommit=$(git rev-list -n 100 "${currentBranch}")

echo "Current branch: ${currentBranch}"
echo "Current commit: ${currentCommit}"
echo "Master commit: ${masterCommit}"

for i in $masterCommit; do
    for j in $currentCommit; do
        if [ "$i" != "$j" ]; then
            echo "BUİLD FAİl: $i"
            exit 0
        fi
    done
done

but it didn't. How can I do it I have to throw the commit numbers into an array and say it failed if it is not in it.