C program(GATE CS 2004)

Consider the following C program

main() {    int x, y, m, n;    scanf ("%d %d", &x, &y);    /* x > 0 and y > 0 */    m = x; n = y;    while (m != n)    {       if(m>n)          m = m - n;       else          n = n - m;    }    printf("%d", n); }

The program computes 
a) x + y using repeated subtraction
b) x mod y using repeated subtraction
c) the greatest common divisor of x and y
d) the least common multiple of x and y

Answer(c)
the greatest common divisor of x and y