string line = "123456";
string s0 = line[0].ToString();
string s1 = line[1].ToString();
string s2 = line[2].ToString();
string s3 = line[3].ToString();
string s4 = line[4].ToString();
string s5 = line[5].ToString();
for(int i=0;i<line.Length;i++) {
project.Variables[string.Format("s_{0}",i)].Value = line[i].ToString();
if(i>5) break;
}