```
public class Solution {
public int uniquePaths(int m, int n) {
int[][] grid = new int[m][n];
for(int i = 0; i<m; i++){
for(int j = 0; j<n; j++){
if(i==0||j==0)
grid[i][j] = 1;
else
grid[i][j] = grid[i][j-1] + grid[i-1][j];
}
}
return grid[m-1][n-1];
}
```

}