int longestWordsPair(String[]strs) {
		int n=strs.length;
		boolean[][] f=new boolean[n][26];
		for (int i=0;i<n;++i) 
			for (char c:strs[i].toCharArray())
				f[i][c-'a']=true;
		int rel=0;
		for (int i=0;i<n;++i) {
			for (int j=i+1;j<n;++j) {
				boolean t=true;
				for (int k=0;k<26&&t;++k) {
					if (f[i][k]&&f[j][k]) {
						t=false;
					}
				}
				if (t) rel=Math.max(rel, strs[i].length()*strs[j].length());
			}
		}
		return rel;
	}