y <- c("1. Stąck is great and awesome", "2. Stack")
regmatches(y, regexpr("\\p{L}+(?:\\s+\\p{L}+){0,2}", y, perl=TRUE))
regmatches(y, regexpr("[[:alpha:]]+(?:[[:space:]]+[[:alpha:]]+){0,2}", y))
eSA8LSBjKCIxLiBTdMSFY2sgaXMgZ3JlYXQgYW5kIGF3ZXNvbWUiLCAiMi4gU3RhY2siKQpyZWdtYXRjaGVzKHksIHJlZ2V4cHIoIlxccHtMfSsoPzpcXHMrXFxwe0x9Kyl7MCwyfSIsIHksIHBlcmw9VFJVRSkpCnJlZ21hdGNoZXMoeSwgcmVnZXhwcigiW1s6YWxwaGE6XV0rKD86W1s6c3BhY2U6XV0rW1s6YWxwaGE6XV0rKXswLDJ9IiwgeSkp