int minDistance(string word1, string word2) {

int n=word1.length();

int m=word2.length();

int dp[n+1][m+1];

for(int i=0;i<=n;i++){

for(int j=0;j<=m;j++){

if(i==0)

dp[i][j]=j;

else if(j==0)

dp[i][j]=i;

else if(word1[i-1]==word2[j-1])

dp[i][j]=dp[i-1][j-1];

else

dp[i][j]=1+min(dp[i-1][j],min(dp[i][j-1],dp[i-1][j-1]));

}

}

return dp[n][m];

}