C program, Function , HELP, 急.

入2 個數, 只出大的那個.
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#include

int max_2_ints(int, int);

int
main (int argc, char **argv) {

int a, b, larger;

printf(" Enter two nubmers:\\n");
scanf(" %d%d", &a, &b);

larger = max_2_ints(x,y);

return 0;
}
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/* MY FUNCTION */

int
max_2_ints(int x, int y){

int larger;
larger =x;
if( y>x)
larger = y;

return larger;

}
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唔明佢點解唔work.
請解釋, THANKS.