int lena = a.length(), lenb = b.length(); for (int i = 1; i <= lena; i++) na[i] = a[lena-i] - '0'; for (int i = 1; i <= lenb; i++) nb[i] = b[lenb-i] - '0';
for (int i = 1; i <= lena + lenb; i++) { nc[i] += na[i] + nb[i]; if (nc[i] >= 10) { nc[i+1]++; nc[i] -= 10; } }
int lenc = lena + lenb + 1; while (lenc > 0 && nc[--lenc] == 0);
char c[10005]; for (int i = lenc; i >= 1; i--) c[lenc-i] = nc[i] + '0'; return c; }
int lena = a.length(), lenb = b.length(); for (int i = 1; i <= lena; i++) na[i] = a[lena-i] - '0'; for (int i = 1; i <= lenb; i++) nb[i] = b[lenb-i] - '0';
for (int i = 1; i <= lena + lenb; i++) { nc[i] += na[i] - nb[i]; if (nc[i] < 0) { nc[i+1]--; nc[i] += 10; } }
int lenc = lena + lenb + 1; while (lenc > 0 && nc[--lenc] == 0);
char c[10005]; for (int i = lenc; i >= 1; i--) c[lenc-i] = nc[i] + '0'; return c; }