import shutil
import os.path
for i in range(len(pairs)):
    if i in train_set:
        s = 'train'
    elif i in test_set:
        s = 'test'
    elif i in val_set:
        s = 'val'

    if os.path.exists('path/to/images/prefix_' + str(pairs[i][0]).zfill(4) + '.png') and os.path.exists('path/to/images/prefix_' + str(pairs[i][1]).zfill(4) + '.png'):
        shutil.copy('path/to/images/prefix_' + str(pairs[i][0]).zfill(4) + '.png', 'A/' + s + '/' + str(pairs[i][0]) + '_' + str(pairs[i][1]) + '.png')
        shutil.copy('path/to/images/prefix_' + str(pairs[i][1]).zfill(4) + '.png', 'B/' + s + '/' + str(pairs[i][0]) + '_' + str(pairs[i][1]) + '.png')