cat
cut

1
R:a->u

a=input().strip(); b=input().strip()
m,n=len(a),len(b)
dp=[[0]*(n+1) for _ in range(m+1)]
for i in range(m+1): dp[i][0]=i
for j in range(n+1): dp[0][j]=j
for i in range(1,m+1):
    for j in range(1,n+1):
        if a[i-1]==b[j-1]: dp[i][j]=dp[i-1][j-1]
        else: dp[i][j]=1+min(dp[i-1][j],dp[i][j-1],dp[i-1][j-1])
print(dp[m][n])
ops=[]; i,j=m,n
while i>0 or j>0:
    if i>0 and j>0 and a[i-1]==b[j-1]: i-=1;j-=1
    elif i>0 and j>0 and dp[i][j]==dp[i-1][j-1]+1: ops.append(f'R:{a[i-1]}->{b[j-1]}');i-=1;j-=1
    elif j>0 and dp[i][j]==dp[i][j-1]+1: ops.append(f'I:{b[j-1]}');j-=1
    else: ops.append(f'D:{a[i-1]}');i-=1
for op in ops[::-1]: print(op)