#include<stdio.h> int MaxCommonFactor( int a, int b) { int c; if(a<=0||b<=0) return -1; while(b!=0) { c=a%b; a=b; b=c; } return a; } int main(void) { /***Begin***/ int a,b; scanf("%d,%d",&a,&b); int c=MaxCommonFactor(a,b); printf("%d\n",c);...