Write a lexical analyzer which reads a C- program

/* A program to perform Euclid's Algorithm to compute gcd. */ int gcd ( int u, int v) { if(v==0) return u ; else return gcd(v, u-u/v*v); /*u-u/v*v == u mod v */ } void main(void) { int x; int y; x=input(); y = input(); output(gcd(x,y)); }