Unique Paths

public class Solution {    public int uniquePaths(int m, int n) {        // Start typing your Java solution below        // DO NOT write main() function        int t = m+n-2;        int low;        long fenmu = 1;        long fenzi = 1;        if(m<n) low = m-1;        else low = n-1;        for(int i =1 ; i <= low; i++){            fenzi = fenzi * t--;            fenmu = fenmu * i;        }        int ret = (int)(fenzi/fenmu);        return ret;     }}